diff --git a/.flake8 b/.flake8
index 090e97971..3f1227b9b 100644
--- a/.flake8
+++ b/.flake8
@@ -2,6 +2,9 @@
 show-source=true
 statistics=true
 max-line-length = 80
+per-file-ignores =
+    # line too long
+    egs/librispeech/ASR/conformer_ctc/conformer.py: E501,
 
 exclude =
   .git,
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 9a298877a..9110e7db4 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -32,7 +32,7 @@ jobs:
         os: [ubuntu-18.04, macos-10.15]
         python-version: [3.6, 3.7, 3.8, 3.9]
         torch: ["1.8.1"]
-        k2-version: ["1.2.dev20210724"]
+        k2-version: ["1.4.dev20210822"]
       fail-fast: false
 
     steps:
@@ -47,16 +47,10 @@ jobs:
 
       - name: Install Python dependencies
         run: |
-          python3 -m pip install --upgrade pip pytest kaldialign
+          python3 -m pip install --upgrade pip pytest
           pip install k2==${{ matrix.k2-version }}+cpu.torch${{ matrix.torch }} -f https://k2-fsa.org/nightly/
-
-          # Don't use: pip install lhotse
-          # since it installs a version of PyTorch that is not predictable
-          git clone --depth 1 https://github.com/lhotse-speech/lhotse
-          cd lhotse
-          sed -i.bak "/torch/d" requirements.txt
-          pip install -r ./requirements.txt
-
+          # icefall requirements
+          pip install -r requirements.txt
 
       - name: Run tests
         if: startsWith(matrix.os, 'ubuntu')
diff --git a/egs/librispeech/ASR/conformer_ctc/conformer.py b/egs/librispeech/ASR/conformer_ctc/conformer.py
index a00664a99..08287d686 100644
--- a/egs/librispeech/ASR/conformer_ctc/conformer.py
+++ b/egs/librispeech/ASR/conformer_ctc/conformer.py
@@ -1,7 +1,20 @@
 #!/usr/bin/env python3
-
 # Copyright (c)  2021  University of Chinese Academy of Sciences (author: Han Zhu)
-# Apache 2.0
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
 import math
 import warnings
@@ -396,7 +409,7 @@ class RelPositionalEncoding(torch.nn.Module):
             :,
             self.pe.size(1) // 2
             - x.size(1)
-            + 1 : self.pe.size(1) // 2
+            + 1 : self.pe.size(1) // 2  # noqa E203
             + x.size(1),
         ]
         return self.dropout(x), self.dropout(pos_emb)
diff --git a/egs/librispeech/ASR/conformer_ctc/decode.py b/egs/librispeech/ASR/conformer_ctc/decode.py
index c540b1ea1..6abcf3385 100755
--- a/egs/librispeech/ASR/conformer_ctc/decode.py
+++ b/egs/librispeech/ASR/conformer_ctc/decode.py
@@ -1,8 +1,20 @@
 #!/usr/bin/env python3
-
 # Copyright 2021 Xiaomi Corporation (Author: Liyong Guo, Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
-# (still working in progress)
 
 import argparse
 import logging
diff --git a/egs/librispeech/ASR/conformer_ctc/pretrained.py b/egs/librispeech/ASR/conformer_ctc/pretrained.py
index c63616d28..95029fadb 100755
--- a/egs/librispeech/ASR/conformer_ctc/pretrained.py
+++ b/egs/librispeech/ASR/conformer_ctc/pretrained.py
@@ -1,4 +1,20 @@
 #!/usr/bin/env python3
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
 import argparse
 import logging
@@ -59,7 +75,7 @@ def get_parser():
             decoding lattice and then use 1best to decode the
             rescored lattice.
             We call it HLG decoding + n-gram LM rescoring.
-        (3) attention-decoder - Extract n paths from he rescored
+        (3) attention-decoder - Extract n paths from the rescored
             lattice and use the transformer attention decoder for
             rescoring.
             We call it HLG decoding + n-gram LM rescoring + attention
@@ -245,9 +261,9 @@ def main():
     if params.method in ["whole-lattice-rescoring", "attention-decoder"]:
         logging.info(f"Loading G from {params.G}")
         G = k2.Fsa.from_dict(torch.load(params.G, map_location="cpu"))
-        G = G.to(device)
         # Add epsilon self-loops to G as we will compose
         # it with the whole lattice later
+        G = G.to(device)
         G = k2.add_epsilon_self_loops(G)
         G = k2.arc_sort(G)
         G.lm_scores = G.scores.clone()
@@ -268,7 +284,7 @@ def main():
     )
     waves = [w.to(device) for w in waves]
 
-    logging.info(f"Decoding started")
+    logging.info("Decoding started")
     features = fbank(waves)
 
     features = pad_sequence(
@@ -338,7 +354,7 @@ def main():
         s += f"{filename}:\n{words}\n\n"
     logging.info(s)
 
-    logging.info(f"Decoding Done")
+    logging.info("Decoding Done")
 
 
 if __name__ == "__main__":
diff --git a/egs/librispeech/ASR/conformer_ctc/subsampling.py b/egs/librispeech/ASR/conformer_ctc/subsampling.py
index 5c3e1222e..720ed6c22 100644
--- a/egs/librispeech/ASR/conformer_ctc/subsampling.py
+++ b/egs/librispeech/ASR/conformer_ctc/subsampling.py
@@ -1,3 +1,20 @@
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
 import torch
 import torch.nn as nn
 
diff --git a/egs/librispeech/ASR/conformer_ctc/test_subsampling.py b/egs/librispeech/ASR/conformer_ctc/test_subsampling.py
index 937845d77..e3361d0c9 100755
--- a/egs/librispeech/ASR/conformer_ctc/test_subsampling.py
+++ b/egs/librispeech/ASR/conformer_ctc/test_subsampling.py
@@ -1,4 +1,20 @@
 #!/usr/bin/env python3
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
 from subsampling import Conv2dSubsampling
 from subsampling import VggSubsampling
diff --git a/egs/librispeech/ASR/conformer_ctc/test_transformer.py b/egs/librispeech/ASR/conformer_ctc/test_transformer.py
index 08e680607..b90215274 100644
--- a/egs/librispeech/ASR/conformer_ctc/test_transformer.py
+++ b/egs/librispeech/ASR/conformer_ctc/test_transformer.py
@@ -1,4 +1,20 @@
 #!/usr/bin/env python3
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
 import torch
 from transformer import (
diff --git a/egs/librispeech/ASR/conformer_ctc/train.py b/egs/librispeech/ASR/conformer_ctc/train.py
index d17ee6164..df9637c34 100755
--- a/egs/librispeech/ASR/conformer_ctc/train.py
+++ b/egs/librispeech/ASR/conformer_ctc/train.py
@@ -1,6 +1,20 @@
 #!/usr/bin/env python3
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
-# This is just at the very beginning ...
 
 import argparse
 import logging
diff --git a/egs/librispeech/ASR/conformer_ctc/transformer.py b/egs/librispeech/ASR/conformer_ctc/transformer.py
index 51c77b220..191d2d612 100644
--- a/egs/librispeech/ASR/conformer_ctc/transformer.py
+++ b/egs/librispeech/ASR/conformer_ctc/transformer.py
@@ -1,5 +1,19 @@
-# Copyright (c) 2021 University of Chinese Academy of Sciences (author: Han Zhu)
-# Apache 2.0
+# Copyright    2021 University of Chinese Academy of Sciences (author: Han Zhu)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
 import math
 from typing import Dict, List, Optional, Tuple
@@ -779,7 +793,8 @@ class Noam(object):
 
 class LabelSmoothingLoss(nn.Module):
     """
-    Label-smoothing loss. KL-divergence between q_{smoothed ground truth prob.}(w)
+    Label-smoothing loss. KL-divergence between
+    q_{smoothed ground truth prob.}(w)
     and p_{prob. computed by model}(w) is minimized.
     Modified from
     https://github.com/espnet/espnet/blob/master/espnet/nets/pytorch_backend/transformer/label_smoothing_loss.py  # noqa
@@ -864,7 +879,8 @@ def encoder_padding_mask(
          frames, before subsampling)
 
     Returns:
-        Tensor: Mask tensor of dimension (batch_size, input_length), True denote the masked indices.
+        Tensor: Mask tensor of dimension (batch_size, input_length),
+        True denote the masked indices.
     """
     if supervisions is None:
         return None
diff --git a/egs/librispeech/ASR/local/compile_hlg.py b/egs/librispeech/ASR/local/compile_hlg.py
index 9f28bb74d..19a1ddd23 100755
--- a/egs/librispeech/ASR/local/compile_hlg.py
+++ b/egs/librispeech/ASR/local/compile_hlg.py
@@ -1,4 +1,20 @@
 #!/usr/bin/env python3
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
 """
 This script takes as input lang_dir and generates HLG from
diff --git a/egs/librispeech/ASR/local/compute_fbank_librispeech.py b/egs/librispeech/ASR/local/compute_fbank_librispeech.py
index d81096070..b89d2dfc2 100755
--- a/egs/librispeech/ASR/local/compute_fbank_librispeech.py
+++ b/egs/librispeech/ASR/local/compute_fbank_librispeech.py
@@ -1,4 +1,20 @@
 #!/usr/bin/env python3
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
 """
 This file computes fbank features of the LibriSpeech dataset.
@@ -17,8 +33,9 @@ from lhotse.recipes.utils import read_manifests_if_cached
 
 from icefall.utils import get_executor
 
-# Torch's multithreaded behavior needs to be disabled or it wastes a lot of CPU and
-# slow things down.  Do this outside of main() in case it needs to take effect
+# Torch's multithreaded behavior needs to be disabled or
+# it wastes a lot of CPU and slow things down.
+# Do this outside of main() in case it needs to take effect
 # even when we are not invoking the main (e.g. when spawning subprocesses).
 torch.set_num_threads(1)
 torch.set_num_interop_threads(1)
@@ -53,7 +70,8 @@ def compute_fbank_librispeech():
                 continue
             logging.info(f"Processing {partition}")
             cut_set = CutSet.from_manifests(
-                recordings=m["recordings"], supervisions=m["supervisions"],
+                recordings=m["recordings"],
+                supervisions=m["supervisions"],
             )
             if "train" in partition:
                 cut_set = (
diff --git a/egs/librispeech/ASR/local/compute_fbank_musan.py b/egs/librispeech/ASR/local/compute_fbank_musan.py
index 0fc515d8c..e10a664b2 100755
--- a/egs/librispeech/ASR/local/compute_fbank_musan.py
+++ b/egs/librispeech/ASR/local/compute_fbank_musan.py
@@ -1,4 +1,20 @@
 #!/usr/bin/env python3
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
 """
 This file computes fbank features of the musan dataset.
@@ -17,8 +33,9 @@ from lhotse.recipes.utils import read_manifests_if_cached
 
 from icefall.utils import get_executor
 
-# Torch's multithreaded behavior needs to be disabled or it wastes a lot of CPU and
-# slow things down.  Do this outside of main() in case it needs to take effect
+# Torch's multithreaded behavior needs to be disabled or
+# it wastes a lot of CPU and slow things down.
+# Do this outside of main() in case it needs to take effect
 # even when we are not invoking the main (e.g. when spawning subprocesses).
 torch.set_num_threads(1)
 torch.set_num_interop_threads(1)
diff --git a/egs/librispeech/ASR/local/download_lm.py b/egs/librispeech/ASR/local/download_lm.py
index 5c9e2a675..94d23afed 100755
--- a/egs/librispeech/ASR/local/download_lm.py
+++ b/egs/librispeech/ASR/local/download_lm.py
@@ -1,6 +1,21 @@
 #!/usr/bin/env python3
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
-# Copyright (c)  2021  Xiaomi Corporation (authors: Fangjun Kuang)
 """
 This file downloads the following LibriSpeech LM files:
 
diff --git a/egs/librispeech/ASR/local/prepare_lang.py b/egs/librispeech/ASR/local/prepare_lang.py
index f7fde7796..0880019b3 100755
--- a/egs/librispeech/ASR/local/prepare_lang.py
+++ b/egs/librispeech/ASR/local/prepare_lang.py
@@ -1,6 +1,20 @@
 #!/usr/bin/env python3
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
-# Copyright (c)  2021  Xiaomi Corporation (authors: Fangjun Kuang)
 
 """
 This script takes as input a lexicon file "data/lang_phone/lexicon.txt"
diff --git a/egs/librispeech/ASR/local/prepare_lang_bpe.py b/egs/librispeech/ASR/local/prepare_lang_bpe.py
index 68b8db966..39d347661 100755
--- a/egs/librispeech/ASR/local/prepare_lang_bpe.py
+++ b/egs/librispeech/ASR/local/prepare_lang_bpe.py
@@ -1,4 +1,20 @@
 #!/usr/bin/env python3
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
 # Copyright (c)  2021  Xiaomi Corporation (authors: Fangjun Kuang)
 
diff --git a/egs/librispeech/ASR/local/test_prepare_lang.py b/egs/librispeech/ASR/local/test_prepare_lang.py
index 23ab53c7d..d4cf62bba 100755
--- a/egs/librispeech/ASR/local/test_prepare_lang.py
+++ b/egs/librispeech/ASR/local/test_prepare_lang.py
@@ -1,4 +1,20 @@
 #!/usr/bin/env python3
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
 # Copyright (c)  2021  Xiaomi Corporation (authors: Fangjun Kuang)
 
diff --git a/egs/librispeech/ASR/local/train_bpe_model.py b/egs/librispeech/ASR/local/train_bpe_model.py
index 9872a7c6a..9ceb181e1 100755
--- a/egs/librispeech/ASR/local/train_bpe_model.py
+++ b/egs/librispeech/ASR/local/train_bpe_model.py
@@ -1,4 +1,20 @@
 #!/usr/bin/env python3
+# Copyright    2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
 # You can install sentencepiece via:
 #
diff --git a/egs/librispeech/ASR/tdnn_lstm_ctc/asr_datamodule.py b/egs/librispeech/ASR/tdnn_lstm_ctc/asr_datamodule.py
index 8d8c7a366..2c3c7252a 100644
--- a/egs/librispeech/ASR/tdnn_lstm_ctc/asr_datamodule.py
+++ b/egs/librispeech/ASR/tdnn_lstm_ctc/asr_datamodule.py
@@ -1,3 +1,20 @@
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
 import argparse
 import logging
 from functools import lru_cache
diff --git a/egs/librispeech/ASR/tdnn_lstm_ctc/decode.py b/egs/librispeech/ASR/tdnn_lstm_ctc/decode.py
index 72f39ef40..130fc16a2 100755
--- a/egs/librispeech/ASR/tdnn_lstm_ctc/decode.py
+++ b/egs/librispeech/ASR/tdnn_lstm_ctc/decode.py
@@ -1,4 +1,19 @@
 #!/usr/bin/env python3
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 
 import argparse
diff --git a/egs/librispeech/ASR/tdnn_lstm_ctc/model.py b/egs/librispeech/ASR/tdnn_lstm_ctc/model.py
index 0dc4228dc..5e04c11b4 100644
--- a/egs/librispeech/ASR/tdnn_lstm_ctc/model.py
+++ b/egs/librispeech/ASR/tdnn_lstm_ctc/model.py
@@ -1,3 +1,20 @@
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
 import torch
 import torch.nn as nn
 
diff --git a/egs/librispeech/ASR/tdnn_lstm_ctc/train.py b/egs/librispeech/ASR/tdnn_lstm_ctc/train.py
index 4adb988a0..23e224f76 100755
--- a/egs/librispeech/ASR/tdnn_lstm_ctc/train.py
+++ b/egs/librispeech/ASR/tdnn_lstm_ctc/train.py
@@ -1,4 +1,20 @@
 #!/usr/bin/env python3
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
 import argparse
 import logging
diff --git a/icefall/bpe_graph_compiler.py b/icefall/bpe_graph_compiler.py
index e22cf4edc..e76b7ea32 100644
--- a/icefall/bpe_graph_compiler.py
+++ b/icefall/bpe_graph_compiler.py
@@ -1,3 +1,20 @@
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
 from pathlib import Path
 from typing import List, Union
 
@@ -57,7 +74,9 @@ class BpeCtcTrainingGraphCompiler(object):
         return self.sp.encode(texts, out_type=int)
 
     def compile(
-        self, piece_ids: List[List[int]], modified: bool = False,
+        self,
+        piece_ids: List[List[int]],
+        modified: bool = False,
     ) -> k2.Fsa:
         """Build a ctc graph from a list-of-list piece IDs.
 
diff --git a/icefall/checkpoint.py b/icefall/checkpoint.py
index a64ecfcf6..b8a628f4e 100644
--- a/icefall/checkpoint.py
+++ b/icefall/checkpoint.py
@@ -1,3 +1,20 @@
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
 import logging
 from pathlib import Path
 from typing import Any, Dict, List, Optional, Union
diff --git a/icefall/dataset/datamodule.py b/icefall/dataset/datamodule.py
index 8560c5db0..97767ef9d 100644
--- a/icefall/dataset/datamodule.py
+++ b/icefall/dataset/datamodule.py
@@ -1,3 +1,20 @@
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
 import argparse
 from typing import List, Union
 
diff --git a/icefall/decode.py b/icefall/decode.py
index 49d642f1c..bcc869e99 100644
--- a/icefall/decode.py
+++ b/icefall/decode.py
@@ -1,3 +1,19 @@
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 import logging
 from typing import Dict, List, Optional, Tuple, Union
 
diff --git a/icefall/dist.py b/icefall/dist.py
index d314d2a43..203c7c563 100644
--- a/icefall/dist.py
+++ b/icefall/dist.py
@@ -1,3 +1,20 @@
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
 import os
 
 import torch
diff --git a/icefall/graph_compiler.py b/icefall/graph_compiler.py
index f7ba3cdaf..23ac247e8 100644
--- a/icefall/graph_compiler.py
+++ b/icefall/graph_compiler.py
@@ -1,3 +1,20 @@
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
 from typing import List
 
 import k2
@@ -8,7 +25,10 @@ from icefall.lexicon import Lexicon
 
 class CtcTrainingGraphCompiler(object):
     def __init__(
-        self, lexicon: Lexicon, device: torch.device, oov: str = "<UNK>",
+        self,
+        lexicon: Lexicon,
+        device: torch.device,
+        oov: str = "<UNK>",
     ):
         """
         Args:
diff --git a/icefall/lexicon.py b/icefall/lexicon.py
index 89747b11b..f1127c7cf 100644
--- a/icefall/lexicon.py
+++ b/icefall/lexicon.py
@@ -1,3 +1,20 @@
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
 import logging
 import re
 import sys
diff --git a/icefall/utils.py b/icefall/utils.py
index 3d48badfe..2994c2d47 100644
--- a/icefall/utils.py
+++ b/icefall/utils.py
@@ -1,3 +1,20 @@
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
 import argparse
 import logging
 import os
diff --git a/test/test_bpe_graph_compiler.py b/test/test_bpe_graph_compiler.py
index 7b941e5a7..67d300b7d 100755
--- a/test/test_bpe_graph_compiler.py
+++ b/test/test_bpe_graph_compiler.py
@@ -1,6 +1,20 @@
 #!/usr/bin/env python3
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
-# Copyright (c)  2021  Xiaomi Corporation (authors: Fangjun Kuang)
 
 from icefall.bpe_graph_compiler import BpeCtcTrainingGraphCompiler
 from icefall.lexicon import BpeLexicon
@@ -15,7 +29,7 @@ def test():
 
     compiler = BpeCtcTrainingGraphCompiler(lang_dir)
     ids = compiler.texts_to_ids(["HELLO", "WORLD ZZZ"])
-    fsa = compiler.compile(ids)
+    compiler.compile(ids)
 
     lexicon = BpeLexicon(lang_dir)
     ids0 = lexicon.words_to_piece_ids(["HELLO"])
diff --git a/test/test_checkpoint.py b/test/test_checkpoint.py
index 343768957..511a11c23 100644
--- a/test/test_checkpoint.py
+++ b/test/test_checkpoint.py
@@ -1,4 +1,20 @@
 #!/usr/bin/env python3
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
 import pytest
 import torch
diff --git a/test/test_graph_compiler.py b/test/test_graph_compiler.py
index 4083d79ac..ccfb57d49 100644
--- a/test/test_graph_compiler.py
+++ b/test/test_graph_compiler.py
@@ -1,6 +1,20 @@
 #!/usr/bin/env python3
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
-# Copyright (c)  2021  Xiaomi Corporation (authors: Fangjun Kuang)
 
 import re
 
diff --git a/test/test_lexicon.py b/test/test_lexicon.py
index b1284d98a..6801b3a89 100644
--- a/test/test_lexicon.py
+++ b/test/test_lexicon.py
@@ -1,4 +1,20 @@
 #!/usr/bin/env python3
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 
 from pathlib import Path
 
diff --git a/test/test_utils.py b/test/test_utils.py
index 27b1ac203..2dd79689f 100644
--- a/test/test_utils.py
+++ b/test/test_utils.py
@@ -1,4 +1,21 @@
 #!/usr/bin/env python3
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
+#
+# See ../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
 import k2
 import pytest
 import torch