diff --git a/setup.py b/setup.py
index 7a22020..ccaf017 100644
--- a/setup.py
+++ b/setup.py
@@ -11,7 +11,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function
 import os
 import re
 
diff --git a/tests/__init__.py b/tests/__init__.py
index 63a267b..1ae7f0c 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016. Mount Sinai School of Medicine
-#
 # 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
diff --git a/tests/benchmark_vcf_load.py b/tests/benchmark_vcf_load.py
index af1476d..0210b46 100644
--- a/tests/benchmark_vcf_load.py
+++ b/tests/benchmark_vcf_load.py
@@ -1,3 +1,15 @@
+# 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.
+
 """
 Time how long it takes to open a VCF.
 
diff --git a/tests/common.py b/tests/common.py
index 999c76f..908dbfc 100644
--- a/tests/common.py
+++ b/tests/common.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016. Mount Sinai School of Medicine
-#
 # 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
diff --git a/tests/data.py b/tests/data.py
index 0335921..79ac90a 100644
--- a/tests/data.py
+++ b/tests/data.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2015. Mount Sinai School of Medicine
-#
 # 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
diff --git a/tests/test_cli_effects.py b/tests/test_cli_effects.py
index 3f8c54f..657d907 100644
--- a/tests/test_cli_effects.py
+++ b/tests/test_cli_effects.py
@@ -1,3 +1,15 @@
+# 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 tempfile import NamedTemporaryFile
 import pandas as pd
 
diff --git a/tests/test_cli_genes.py b/tests/test_cli_genes.py
index 79c347a..06c9a60 100644
--- a/tests/test_cli_genes.py
+++ b/tests/test_cli_genes.py
@@ -1,3 +1,15 @@
+# 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 varcode.cli.genes_script import main as run_script
 from .data import ov_wustle_variants, db_snp_variants
 
diff --git a/tests/test_collection_filtering.py b/tests/test_collection_filtering.py
index c68cc25..964d242 100644
--- a/tests/test_collection_filtering.py
+++ b/tests/test_collection_filtering.py
@@ -10,9 +10,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from nose.tools import eq_
-from varcode import VariantCollection
 
+from varcode import VariantCollection
+from .common import eq_
 from .data import (
     snp_rs4244285,
     snp_rs1537415
diff --git a/tests/test_common.py b/tests/test_common.py
index a2cdad0..dee73af 100644
--- a/tests/test_common.py
+++ b/tests/test_common.py
@@ -10,8 +10,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from nose.tools import eq_
 import varcode
+from .common import eq_
 
 def test_memoize():
     class State(object):
diff --git a/tests/test_effect_collection.py b/tests/test_effect_collection.py
index 859784b..e0d6c7a 100644
--- a/tests/test_effect_collection.py
+++ b/tests/test_effect_collection.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016. Mount Sinai School of Medicine
-#
 # 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
diff --git a/tests/test_effect_collection_serialization.py b/tests/test_effect_collection_serialization.py
index c172f73..514a559 100644
--- a/tests/test_effect_collection_serialization.py
+++ b/tests/test_effect_collection_serialization.py
@@ -1,4 +1,16 @@
 
+# 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 pickle
 
 from varcode import EffectCollection
diff --git a/tests/test_exonic_splice_site.py b/tests/test_exonic_splice_site.py
index e756561..63b53dd 100644
--- a/tests/test_exonic_splice_site.py
+++ b/tests/test_exonic_splice_site.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2018. Mount Sinai School of Medicine
-#
 # 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
diff --git a/tests/test_frameshift_helpers.py b/tests/test_frameshift_helpers.py
index 9b1dea7..6f7c725 100644
--- a/tests/test_frameshift_helpers.py
+++ b/tests/test_frameshift_helpers.py
@@ -1,3 +1,15 @@
+# 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 varcode.effects.effect_prediction_coding_frameshift import (
     cdna_codon_sequence_after_insertion_frameshift,
     cdna_codon_sequence_after_deletion_or_substitution_frameshift,
diff --git a/tests/test_mm10_klf6_frameshift.py b/tests/test_mm10_klf6_frameshift.py
index 4aade48..3012bea 100644
--- a/tests/test_mm10_klf6_frameshift.py
+++ b/tests/test_mm10_klf6_frameshift.py
@@ -1,3 +1,15 @@
+# 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 varcode import Variant
 from varcode.effects import FrameShift
 from varcode.effects.effect_prediction_coding_frameshift import (
diff --git a/tests/test_mouse.py b/tests/test_mouse.py
index d3cd588..319e916 100644
--- a/tests/test_mouse.py
+++ b/tests/test_mouse.py
@@ -1,4 +1,14 @@
-from __future__ import absolute_import
+# 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 .common import eq_
 
diff --git a/tests/test_mutate.py b/tests/test_mutate.py
index 64c4b0a..258758d 100644
--- a/tests/test_mutate.py
+++ b/tests/test_mutate.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2015. Mount Sinai School of Medicine
-#
 # 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
diff --git a/tests/test_no_duplicate_variants.py b/tests/test_no_duplicate_variants.py
index 11a061e..6c88f61 100644
--- a/tests/test_no_duplicate_variants.py
+++ b/tests/test_no_duplicate_variants.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2015. Mount Sinai School of Medicine
-#
 # 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
diff --git a/tests/test_string_helpers.py b/tests/test_string_helpers.py
index ae5592e..0fbc8a5 100644
--- a/tests/test_string_helpers.py
+++ b/tests/test_string_helpers.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2015. Mount Sinai School of Medicine
-#
 # 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
diff --git a/tests/test_timings.py b/tests/test_timings.py
index 92c3cb9..3666889 100644
--- a/tests/test_timings.py
+++ b/tests/test_timings.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2015. Mount Sinai School of Medicine
-#
 # 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
diff --git a/tests/test_variant.py b/tests/test_variant.py
index 0a4acf2..894ab65 100644
--- a/tests/test_variant.py
+++ b/tests/test_variant.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2015. Mount Sinai School of Medicine
-#
 # 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
diff --git a/tests/test_variant_collection.py b/tests/test_variant_collection.py
index 1b628dd..5efa15f 100644
--- a/tests/test_variant_collection.py
+++ b/tests/test_variant_collection.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2015. Mount Sinai School of Medicine
-#
 # 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
diff --git a/varcode/cli/__init__.py b/varcode/cli/__init__.py
index f21d5b4..693cc44 100644
--- a/varcode/cli/__init__.py
+++ b/varcode/cli/__init__.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016. Mount Sinai School of Medicine
-#
 # 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
@@ -12,8 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
-
 from .variant_args import (
     add_variant_args,
     make_variants_parser,
diff --git a/varcode/cli/effects_script.py b/varcode/cli/effects_script.py
index 22094a4..475671b 100644
--- a/varcode/cli/effects_script.py
+++ b/varcode/cli/effects_script.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2019. Mount Sinai School of Medicine
-#
 # 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
@@ -12,8 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import division, absolute_import
-
 import logging.config
 import pkg_resources
 import sys
diff --git a/varcode/cli/genes_script.py b/varcode/cli/genes_script.py
index 16f8441..146d454 100644
--- a/varcode/cli/genes_script.py
+++ b/varcode/cli/genes_script.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2019. Mount Sinai School of Medicine
-#
 # 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
@@ -12,7 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import division, absolute_import
 import logging
 import logging.config
 import pkg_resources
diff --git a/varcode/cli/variant_args.py b/varcode/cli/variant_args.py
index 810c089..756415a 100644
--- a/varcode/cli/variant_args.py
+++ b/varcode/cli/variant_args.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2019. Mount Sinai School of Medicine
-#
 # 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
@@ -12,7 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
 from argparse import ArgumentParser
 
 from ..vcf import load_vcf
diff --git a/varcode/cli/version_info.py b/varcode/cli/version_info.py
index 11b0e6f..e083dc6 100644
--- a/varcode/cli/version_info.py
+++ b/varcode/cli/version_info.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2018. Mount Sinai School of Medicine
-#
 # 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
@@ -12,8 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
-
 from collections import OrderedDict
 from os.path import dirname
 from .. import __file__ as package_init_file_path
diff --git a/varcode/common.py b/varcode/common.py
index 799a264..5c5020d 100644
--- a/varcode/common.py
+++ b/varcode/common.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2019. Mount Sinai School of Medicine
-#
 # 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
@@ -12,7 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
 from collections import defaultdict
 
 from functools import wraps
diff --git a/varcode/effects/__init__.py b/varcode/effects/__init__.py
index 21f2e51..c98462b 100644
--- a/varcode/effects/__init__.py
+++ b/varcode/effects/__init__.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016. Mount Sinai School of Medicine
-#
 # 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
diff --git a/varcode/effects/common.py b/varcode/effects/common.py
index c14256d..d39358f 100644
--- a/varcode/effects/common.py
+++ b/varcode/effects/common.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016. Mount Sinai School of Medicine
-#
 # 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
@@ -12,15 +10,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
-
 from Bio.Seq import Seq
-from six import string_types, text_type
+
 
 
 def bio_seq_to_str(seq):
-    if isinstance(seq, Seq):
-        return str(seq)
-    elif isinstance(seq, string_types):
-        return text_type(seq)
-    return seq
+    if type(seq) is str:
+        return seq
+    else:
+        return str(seq) 
+    
\ No newline at end of file
diff --git a/varcode/effects/effect_classes.py b/varcode/effects/effect_classes.py
index 978cfef..5bb544a 100644
--- a/varcode/effects/effect_classes.py
+++ b/varcode/effects/effect_classes.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2018. Mount Sinai School of Medicine
-#
 # 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
@@ -12,7 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
 
 from memoized_property import memoized_property
 from serializable import Serializable
diff --git a/varcode/effects/effect_collection.py b/varcode/effects/effect_collection.py
index b8d88a0..de1f381 100644
--- a/varcode/effects/effect_collection.py
+++ b/varcode/effects/effect_collection.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016. Mount Sinai School of Medicine
-#
 # 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
@@ -12,7 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
 from collections import OrderedDict
 
 import pandas as pd
diff --git a/varcode/effects/effect_helpers.py b/varcode/effects/effect_helpers.py
index 4eb840f..0f6aff8 100644
--- a/varcode/effects/effect_helpers.py
+++ b/varcode/effects/effect_helpers.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016. Mount Sinai School of Medicine
-#
 # 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
@@ -16,7 +14,6 @@
 Helper functions for determine effect annotation for a variant
 """
 
-from __future__ import print_function, division, absolute_import
 
 from ..nucleotides import PURINE_NUCLEOTIDES, AMINO_NUCLEOTIDES
 
diff --git a/varcode/effects/effect_ordering.py b/varcode/effects/effect_ordering.py
index f13c07d..38f6112 100644
--- a/varcode/effects/effect_ordering.py
+++ b/varcode/effects/effect_ordering.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016. Mount Sinai School of Medicine
-#
 # 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
@@ -12,8 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
-
 from .effect_classes import (
     Failure,
     IncompleteTranscript,
diff --git a/varcode/effects/effect_prediction.py b/varcode/effects/effect_prediction.py
index b45fb7a..f38b80a 100644
--- a/varcode/effects/effect_prediction.py
+++ b/varcode/effects/effect_prediction.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2019. Mount Sinai School of Medicine
-#
 # 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
@@ -12,7 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
 import logging
 
 from Bio.Seq import reverse_complement
diff --git a/varcode/effects/effect_prediction_coding.py b/varcode/effects/effect_prediction_coding.py
index 768ab7e..7069a9b 100644
--- a/varcode/effects/effect_prediction_coding.py
+++ b/varcode/effects/effect_prediction_coding.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2018. Mount Sinai School of Medicine
-#
 # 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
@@ -12,8 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
-
 from .effect_prediction_coding_frameshift import predict_frameshift_coding_effect
 from .effect_prediction_coding_in_frame import predict_in_frame_coding_effect
 
diff --git a/varcode/effects/effect_prediction_coding_frameshift.py b/varcode/effects/effect_prediction_coding_frameshift.py
index cd3a9c9..7a17261 100644
--- a/varcode/effects/effect_prediction_coding_frameshift.py
+++ b/varcode/effects/effect_prediction_coding_frameshift.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2018. Mount Sinai School of Medicine
-#
 # 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
@@ -17,8 +15,6 @@
 reading frame.
 """
 
-from __future__ import print_function, division, absolute_import
-
 from ..string_helpers import trim_shared_prefix
 
 from .effect_classes import (
diff --git a/varcode/effects/effect_prediction_coding_in_frame.py b/varcode/effects/effect_prediction_coding_in_frame.py
index af0d329..58e1c38 100644
--- a/varcode/effects/effect_prediction_coding_in_frame.py
+++ b/varcode/effects/effect_prediction_coding_in_frame.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2018. Mount Sinai School of Medicine
-#
 # 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
@@ -16,7 +14,6 @@
 Effect annotation for variants which modify the coding sequence without
 changing the reading frame.
 """
-from __future__ import division, absolute_import, print_function
 
 from ..string_helpers import trim_shared_flanking_strings
 from .effect_classes import (
diff --git a/varcode/effects/mutate.py b/varcode/effects/mutate.py
index 76c53d2..77f3be7 100644
--- a/varcode/effects/mutate.py
+++ b/varcode/effects/mutate.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016. Mount Sinai School of Medicine
-#
 # 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
@@ -12,8 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
-
 
 def insert_before(sequence, offset, new_residues):
     """Mutate the given sequence by inserting the string `new_residues` before
diff --git a/varcode/effects/transcript_helpers.py b/varcode/effects/transcript_helpers.py
index 3483183..186e944 100644
--- a/varcode/effects/transcript_helpers.py
+++ b/varcode/effects/transcript_helpers.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016. Mount Sinai School of Medicine
-#
 # 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
@@ -12,8 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
-
 
 def interval_offset_on_transcript(start, end, transcript):
     """
diff --git a/varcode/effects/translate.py b/varcode/effects/translate.py
index 174280d..016015d 100644
--- a/varcode/effects/translate.py
+++ b/varcode/effects/translate.py
@@ -1,4 +1,3 @@
-#
 # 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
@@ -16,8 +15,6 @@
 TODO: generalize this to work with the mitochondrial codon table.
 """
 
-from __future__ import division, absolute_import, print_function
-
 from Bio.Data import CodonTable
 from Bio.Seq import Seq
 
diff --git a/varcode/maf.py b/varcode/maf.py
index 556d7fe..fba4220 100644
--- a/varcode/maf.py
+++ b/varcode/maf.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2017. Mount Sinai School of Medicine
-#
 # 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
@@ -12,7 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
 import logging
 
 import pandas
diff --git a/varcode/nucleotides.py b/varcode/nucleotides.py
index d20c71e..28ba029 100644
--- a/varcode/nucleotides.py
+++ b/varcode/nucleotides.py
@@ -1,4 +1,3 @@
-#
 # 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
diff --git a/varcode/reference.py b/varcode/reference.py
index 34177e0..8b8be26 100644
--- a/varcode/reference.py
+++ b/varcode/reference.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2018. Mount Sinai School of Medicine
-#
 # 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
diff --git a/varcode/string_helpers.py b/varcode/string_helpers.py
index d792bb7..efeed07 100644
--- a/varcode/string_helpers.py
+++ b/varcode/string_helpers.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016. Mount Sinai School of Medicine
-#
 # 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
diff --git a/varcode/ucsc_reference_names.py b/varcode/ucsc_reference_names.py
index 07adf8d..3649965 100644
--- a/varcode/ucsc_reference_names.py
+++ b/varcode/ucsc_reference_names.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2019. Mount Sinai School of Medicine
-#
 # 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
diff --git a/varcode/util.py b/varcode/util.py
index e1fc750..61fc698 100644
--- a/varcode/util.py
+++ b/varcode/util.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016. Mount Sinai School of Medicine
-#
 # 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
@@ -12,11 +10,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
 import random
 
 from Bio.Seq import reverse_complement
-from pyensembl import EnsemblRelease
 from pyensembl import genome_for_reference_name
 
 from .nucleotides import STANDARD_NUCLEOTIDES
diff --git a/varcode/variant.py b/varcode/variant.py
index ef9f474..56acc2c 100644
--- a/varcode/variant.py
+++ b/varcode/variant.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2019. Mount Sinai School of Medicine
-#
 # 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
@@ -12,8 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
-
 from pyensembl.locus import normalize_chromosome
 from serializable import Serializable
 from typechecks import require_instance
diff --git a/varcode/variant_collection.py b/varcode/variant_collection.py
index a57ac94..9faea44 100644
--- a/varcode/variant_collection.py
+++ b/varcode/variant_collection.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2019. Mount Sinai School of Medicine
-#
 # 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
@@ -12,8 +10,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function, division, absolute_import
-
 from collections import OrderedDict
 
 import pandas as pd
diff --git a/varcode/vcf.py b/varcode/vcf.py
index 5f248ea..f4ca45d 100644
--- a/varcode/vcf.py
+++ b/varcode/vcf.py
@@ -1,4 +1,3 @@
-#
 # 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
@@ -12,7 +11,6 @@
 # limitations under the License.
 
 
-from __future__ import absolute_import, print_function, division
 import os
 import requests
 import zlib
diff --git a/varcode/vcf_output.py b/varcode/vcf_output.py
index 2f2c4fb..ec5d89f 100644
--- a/varcode/vcf_output.py
+++ b/varcode/vcf_output.py
@@ -1,5 +1,3 @@
-# Copyright (c) 2016-2018. Mount Sinai School of Medicine
-#
 # 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
@@ -13,7 +11,6 @@
 # limitations under the License.
 
 
-from __future__ import absolute_import, print_function, division
 from collections import defaultdict
 import sys