diff --git a/python/paddle/__init__.py b/python/paddle/__init__.py
index fc8a9b52bc08f1c691703aaeba0da72667a7dfc1..95e179bb97dc89bbcb08a61ce699be15004c06b7 100755
--- a/python/paddle/__init__.py
+++ b/python/paddle/__init__.py
@@ -61,7 +61,6 @@ else:
     from .framework import VarBase as Tensor  # noqa: F401
 
 Tensor.__qualname__ = 'Tensor'  # noqa: F401
-import paddle.compat  # noqa: F401
 import paddle.distributed  # noqa: F401
 import paddle.sysconfig  # noqa: F401
 import paddle.distribution  # noqa: F401
diff --git a/python/paddle/compat.py b/python/paddle/compat.py
deleted file mode 100644
index dfa9f1822bff8dd0bf538bd31eb0aa8ec8501372..0000000000000000000000000000000000000000
--- a/python/paddle/compat.py
+++ /dev/null
@@ -1,198 +0,0 @@
-#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
-#
-# 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 six
-
-__all__ = []
-
-
-#  str and bytes related functions
-def to_text(obj, encoding='utf-8', inplace=False):
-    """
-    All string in PaddlePaddle should be represented as a literal string.
-
-    This function will convert object to a literal string without any encoding.
-    Especially, if the object type is a list or set container, we will iterate
-    all items in the object and convert them to literal string.
-
-    In Python3:
-        Decode the bytes type object to str type with specific encoding
-
-    In Python2:
-        Decode the str type object to unicode type with specific encoding
-
-    Args:
-        obj(unicode|str|bytes|list|set) : The object to be decoded.
-        encoding(str) : The encoding format to decode a string
-        inplace(bool) : If we change the original object or we create a new one
-
-    Returns:
-        Decoded result of obj
-
-    Examples:
-
-        .. code-block:: python
-
-            import paddle
-
-            data = "paddlepaddle"
-            data = paddle.compat.to_text(data)
-            # paddlepaddle
-
-    """
-    if obj is None:
-        return obj
-
-    if isinstance(obj, list):
-        if inplace:
-            for i in six.moves.xrange(len(obj)):
-                obj[i] = _to_text(obj[i], encoding)
-            return obj
-        else:
-            return [_to_text(item, encoding) for item in obj]
-    elif isinstance(obj, set):
-        if inplace:
-            for item in obj:
-                obj.remove(item)
-                obj.add(_to_text(item, encoding))
-            return obj
-        else:
-            return set([_to_text(item, encoding) for item in obj])
-    elif isinstance(obj, dict):
-        if inplace:
-            new_obj = {}
-            for key, value in six.iteritems(obj):
-                new_obj[_to_text(key, encoding)] = _to_text(value, encoding)
-            obj.update(new_obj)
-            return obj
-        else:
-            new_obj = {}
-            for key, value in six.iteritems(obj):
-                new_obj[_to_text(key, encoding)] = _to_text(value, encoding)
-            return new_obj
-    else:
-        return _to_text(obj, encoding)
-
-
-def _to_text(obj, encoding):
-    """
-    In Python3:
-        Decode the bytes type object to str type with specific encoding
-
-    In Python2:
-        Decode the str type object to unicode type with specific encoding,
-        or we just return the unicode string of object
-
-    Args:
-        obj(unicode|str|bytes) : The object to be decoded.
-        encoding(str) : The encoding format
-
-    Returns:
-        decoded result of obj
-    """
-    if obj is None:
-        return obj
-
-    if isinstance(obj, six.binary_type):
-        return obj.decode(encoding)
-    elif isinstance(obj, six.text_type):
-        return obj
-    elif isinstance(obj, (bool, float)):
-        return obj
-    else:
-        return six.u(obj)
-
-
-def to_bytes(obj, encoding='utf-8', inplace=False):
-    """
-    All string in PaddlePaddle should be represented as a literal string.
-
-    This function will convert object to a bytes with specific encoding.
-    Especially, if the object type is a list or set container, we will iterate
-    all items in the object and convert them to bytes.
-
-    In Python3:
-        Encode the str type object to bytes type with specific encoding
-
-    In Python2:
-        Encode the unicode type object to str type with specific encoding,
-        or we just return the 8-bit string of object
-
-    Args:
-        obj(unicode|str|bytes|list|set) : The object to be encoded.
-        encoding(str) : The encoding format to encode a string
-        inplace(bool) : If we change the original object or we create a new one
-
-    Returns:
-        Decoded result of obj
-
-    Examples:
-
-        .. code-block:: python
-
-            import paddle
-
-            data = "paddlepaddle"
-            data = paddle.compat.to_bytes(data)
-            # b'paddlepaddle'
-
-    """
-    if obj is None:
-        return obj
-
-    if isinstance(obj, list):
-        if inplace:
-            for i in six.moves.xrange(len(obj)):
-                obj[i] = _to_bytes(obj[i], encoding)
-            return obj
-        else:
-            return [_to_bytes(item, encoding) for item in obj]
-    elif isinstance(obj, set):
-        if inplace:
-            for item in obj:
-                obj.remove(item)
-                obj.add(_to_bytes(item, encoding))
-            return obj
-        else:
-            return set([_to_bytes(item, encoding) for item in obj])
-    else:
-        return _to_bytes(obj, encoding)
-
-
-def _to_bytes(obj, encoding):
-    """
-    In Python3:
-        Encode the str type object to bytes type with specific encoding
-
-    In Python2:
-        Encode the unicode type object to str type with specific encoding,
-        or we just return the 8-bit string of object
-
-    Args:
-        obj(unicode|str|bytes) : The object to be encoded.
-        encoding(str) : The encoding format
-
-    Returns:
-        encoded result of obj
-    """
-    if obj is None:
-        return obj
-
-    assert encoding is not None
-    if isinstance(obj, six.text_type):
-        return obj.encode(encoding)
-    elif isinstance(obj, six.binary_type):
-        return obj
-    else:
-        return six.b(obj)
diff --git a/python/paddle/fluid/backward.py b/python/paddle/fluid/backward.py
index 16708268bd5a0b044a6790a7db42747089789382..7823b3f7bd47a97ab53ef3f171b02e0c3ca8e105 100755
--- a/python/paddle/fluid/backward.py
+++ b/python/paddle/fluid/backward.py
@@ -20,7 +20,6 @@ from . import core
 import collections
 import copy
 import logging
-from .. import compat as cpt
 from . import unique_name
 from . import log_helper
 import paddle.fluid
diff --git a/python/paddle/fluid/core.py b/python/paddle/fluid/core.py
index 00f7abee30e21b71dbec894d5819e31e7ad0b0d3..718ddd4bd56310d58362e38a231254f810090795 100644
--- a/python/paddle/fluid/core.py
+++ b/python/paddle/fluid/core.py
@@ -44,8 +44,6 @@ try:
             os.add_dll_directory(third_lib_path)
 
 except ImportError as e:
-    from .. import compat as cpt
-
     if os.name == 'nt':
         executable_path = os.path.abspath(os.path.dirname(sys.executable))
         raise ImportError(
@@ -71,8 +69,6 @@ def avx_supported():
     """
     Whether current system(Linux, MacOS, Windows) is supported with AVX.
     """
-    from .. import compat as cpt
-
     sysstr = platform.system().lower()
     has_avx = False
     if sysstr == 'linux':
diff --git a/python/paddle/fluid/dygraph/io.py b/python/paddle/fluid/dygraph/io.py
index d2e7ada85a7568bceb1d87e389eafebb20813cc3..c5eb445cc610d2fa3d07f239fa3f69737e7d174d 100644
--- a/python/paddle/fluid/dygraph/io.py
+++ b/python/paddle/fluid/dygraph/io.py
@@ -17,7 +17,6 @@ import pickle
 import numpy as np
 
 import paddle
-from paddle import compat as cpt
 from paddle.fluid import core
 from paddle.fluid import framework
 from paddle.fluid import backward
diff --git a/python/paddle/fluid/framework.py b/python/paddle/fluid/framework.py
index 46bd46d706ae2451b3fbd48ca2bb68a09f560d0e..2cceeabfc4c23c9d1e0578423782e2c42b279096 100644
--- a/python/paddle/fluid/framework.py
+++ b/python/paddle/fluid/framework.py
@@ -28,7 +28,6 @@ import subprocess
 import multiprocessing
 import sys
 import logging
-from .. import compat as cpt
 from .proto import framework_pb2
 
 from . import core
diff --git a/python/paddle/fluid/layers/control_flow.py b/python/paddle/fluid/layers/control_flow.py
index 1046c27fef54dfdfd634ce5050b1668326364b1f..18b2ec496499d1e2decdd0fc0b03bd771a9c5085 100755
--- a/python/paddle/fluid/layers/control_flow.py
+++ b/python/paddle/fluid/layers/control_flow.py
@@ -48,7 +48,6 @@ from ..data_feeder import (
     check_type,
     check_dtype,
 )
-from ... import compat as cpt
 from ..backward import _infer_var_data_type_shape_
 from paddle import _C_ops, _legacy_C_ops
 
diff --git a/python/paddle/fluid/layers/detection.py b/python/paddle/fluid/layers/detection.py
index 0711bddb45dd58ec802257e9e41a5a61ce77792d..097875a75f2e8a831fb8d90443c8652eb4eabd72 100644
--- a/python/paddle/fluid/layers/detection.py
+++ b/python/paddle/fluid/layers/detection.py
@@ -26,7 +26,6 @@ from .loss import softmax_with_cross_entropy
 from . import tensor
 from . import nn
 from . import ops
-from ... import compat as cpt
 from ..data_feeder import check_variable_and_dtype, check_type, check_dtype
 import math
 import numpy as np
diff --git a/python/paddle/fluid/optimizer.py b/python/paddle/fluid/optimizer.py
index ce58c0cfe02fbce2bbf08b8083603de6a8ddd1eb..f06c380838f151d37a2e383e42eb0ecf0d8cce25 100755
--- a/python/paddle/fluid/optimizer.py
+++ b/python/paddle/fluid/optimizer.py
@@ -60,7 +60,6 @@ from paddle.fluid.layers import tensor
 from functools import reduce
 from functools import cmp_to_key
 from .wrapped_decorator import signature_safe_contextmanager
-from .. import compat as cpt
 import warnings
 from paddle import _C_ops, _legacy_C_ops
 from ..fluid.framework import (
@@ -6933,9 +6932,10 @@ class RecomputeOptimizer(Optimizer):
         Examples:
             .. code-block:: python
 
+                import paddle
                 import paddle.fluid as fluid
-                import paddle.compat as cpt
 
+                paddle.enable_static()
                 def mlp(input_x, input_y, hid_dim=128, label_dim=2):
                     fc_1 = fluid.layers.fc(input=input_x, size=hid_dim)
                     prediction = fluid.layers.fc(input=[fc_1], size=label_dim, act='softmax')
@@ -6955,7 +6955,7 @@ class RecomputeOptimizer(Optimizer):
                     state_dict = {}
                     sgd.load(state_dict)
                 except NotImplementedError as e:
-                    print(cpt.get_exception_message(e))
+                    print(e)
         """
         raise NotImplementedError(
             "load function is not supported by Recompute Optimizer for now"
diff --git a/python/paddle/fluid/tests/unittests/mlu/test_collective_api_base_mlu.py b/python/paddle/fluid/tests/unittests/mlu/test_collective_api_base_mlu.py
index 26e7c2972b3311acc6cdc555f44f3a637e408327..5adcf7a29875af054fad9e7b20633de9462cfae7 100644
--- a/python/paddle/fluid/tests/unittests/mlu/test_collective_api_base_mlu.py
+++ b/python/paddle/fluid/tests/unittests/mlu/test_collective_api_base_mlu.py
@@ -89,7 +89,6 @@ def runtime_main(test_class, col_type):
     model.run_trainer(args)
 
 
-import paddle.compat as cpt
 import socket
 from contextlib import closing
 
diff --git a/python/paddle/fluid/tests/unittests/mlu/test_collective_base_mlu.py b/python/paddle/fluid/tests/unittests/mlu/test_collective_base_mlu.py
index ab089aa26b7741f8869712d03a5ccd6002027db7..3e005bafb4131bc073daea78f9539a82215b9629 100644
--- a/python/paddle/fluid/tests/unittests/mlu/test_collective_base_mlu.py
+++ b/python/paddle/fluid/tests/unittests/mlu/test_collective_base_mlu.py
@@ -163,7 +163,6 @@ def runtime_main(test_class):
     model.run_trainer(args)
 
 
-import paddle.compat as cpt
 import socket
 from contextlib import closing
 
diff --git a/python/paddle/fluid/tests/unittests/mlu/test_fill_constant_batch_size_like_op_mlu.py b/python/paddle/fluid/tests/unittests/mlu/test_fill_constant_batch_size_like_op_mlu.py
index 79b5d7abe7d82e28b6d026a7e5abc10512b066f5..927c0627e2f397edc8ca021f8b7edf7d3ed92e49 100644
--- a/python/paddle/fluid/tests/unittests/mlu/test_fill_constant_batch_size_like_op_mlu.py
+++ b/python/paddle/fluid/tests/unittests/mlu/test_fill_constant_batch_size_like_op_mlu.py
@@ -18,7 +18,6 @@ sys.path.append("..")
 import paddle
 import paddle.fluid.core as core
 from paddle.static import program_guard, Program
-import paddle.compat as cpt
 import unittest
 import numpy as np
 from op_test import OpTest
diff --git a/python/paddle/fluid/tests/unittests/mlu/test_sync_batch_norm_base_mlu.py b/python/paddle/fluid/tests/unittests/mlu/test_sync_batch_norm_base_mlu.py
index dd842800198cb42487ff7e943567c533466f23e0..cb7a890adb22271d993c05323c45ae9bd407e1e7 100644
--- a/python/paddle/fluid/tests/unittests/mlu/test_sync_batch_norm_base_mlu.py
+++ b/python/paddle/fluid/tests/unittests/mlu/test_sync_batch_norm_base_mlu.py
@@ -434,7 +434,6 @@ def runtime_main(test_class, col_type, sub_type):
     model.run_trainer(args)
 
 
-import paddle.compat as cpt
 import socket
 from contextlib import closing
 
diff --git a/python/paddle/fluid/tests/unittests/npu/test_collective_base_npu.py b/python/paddle/fluid/tests/unittests/npu/test_collective_base_npu.py
index 6b7e056a7f86a6832be2899dd4e29abbf64f2fd2..55bc9dce1863ef15ffd1bd58939e38393270c8ad 100644
--- a/python/paddle/fluid/tests/unittests/npu/test_collective_base_npu.py
+++ b/python/paddle/fluid/tests/unittests/npu/test_collective_base_npu.py
@@ -138,7 +138,6 @@ def runtime_main(test_class, col_type, sub_type):
     model.run_trainer(args)
 
 
-import paddle.compat as cpt
 import socket
 from contextlib import closing
 
diff --git a/python/paddle/fluid/tests/unittests/npu/test_sync_batch_norm_base_npu.py b/python/paddle/fluid/tests/unittests/npu/test_sync_batch_norm_base_npu.py
index 1629c8e8fb20a8d70190482f0598c12719115dd1..101a749f424913d3e57a138b6b308cb8383319e4 100644
--- a/python/paddle/fluid/tests/unittests/npu/test_sync_batch_norm_base_npu.py
+++ b/python/paddle/fluid/tests/unittests/npu/test_sync_batch_norm_base_npu.py
@@ -451,7 +451,6 @@ def runtime_main(test_class, col_type, sub_type):
     model.run_trainer(args)
 
 
-import paddle.compat as cpt
 import socket
 from contextlib import closing
 
diff --git a/python/paddle/fluid/tests/unittests/test_compat.py b/python/paddle/fluid/tests/unittests/test_compat.py
deleted file mode 100644
index d4ad8a8274e3a8b36f4eb195fae2bade5716b280..0000000000000000000000000000000000000000
--- a/python/paddle/fluid/tests/unittests/test_compat.py
+++ /dev/null
@@ -1,240 +0,0 @@
-#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
-#
-# 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 unittest
-import paddle.compat as cpt
-
-
-class TestCompatible(unittest.TestCase):
-    def test_to_text(self):
-        self.assertIsNone(cpt.to_text(None))
-
-        self.assertTrue(isinstance(cpt.to_text(str("")), str))
-        self.assertTrue(isinstance(cpt.to_text(str("123")), str))
-        self.assertTrue(isinstance(cpt.to_text(b""), str))
-        self.assertTrue(isinstance(cpt.to_text(b""), str))
-        self.assertTrue(isinstance(cpt.to_text(u""), str))
-        self.assertTrue(isinstance(cpt.to_text(u""), str))
-
-        self.assertEqual("", cpt.to_text(str("")))
-        self.assertEqual("123", cpt.to_text(str("123")))
-        self.assertEqual("", cpt.to_text(b""))
-        self.assertEqual("123", cpt.to_text(b"123"))
-        self.assertEqual("", cpt.to_text(u""))
-        self.assertEqual("123", cpt.to_text(u"123"))
-
-        # check list types, not inplace
-        l = [""]
-        l2 = cpt.to_text(l)
-        self.assertTrue(isinstance(l2, list))
-        self.assertFalse(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual([""], l2)
-        l = ["", "123"]
-        l2 = cpt.to_text(l)
-        self.assertTrue(isinstance(l2, list))
-        self.assertFalse(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual(["", "123"], l2)
-        l = ["", b"123", u"321"]
-        l2 = cpt.to_text(l)
-        self.assertTrue(isinstance(l2, list))
-        self.assertFalse(l is l2)
-        self.assertNotEqual(l, l2)
-        self.assertEqual(["", "123", "321"], l2)
-
-        # check list types, inplace
-        l = [""]
-        l2 = cpt.to_text(l, inplace=True)
-        self.assertTrue(isinstance(l2, list))
-        self.assertTrue(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual([""], l2)
-        l = ["", b"123"]
-        l2 = cpt.to_text(l, inplace=True)
-        self.assertTrue(isinstance(l2, list))
-        self.assertTrue(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual(["", "123"], l2)
-        l = ["", b"123", u"321"]
-        l2 = cpt.to_text(l, inplace=True)
-        self.assertTrue(isinstance(l2, list))
-        self.assertTrue(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual(["", "123", "321"], l2)
-        for i in l2:
-            self.assertTrue(isinstance(i, str))
-
-        # check set types, not inplace
-        l = set("")
-        l2 = cpt.to_text(l, inplace=False)
-        self.assertTrue(isinstance(l2, set))
-        self.assertFalse(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual(set(""), l2)
-        l = set([b"", b"123"])
-        l2 = cpt.to_text(l, inplace=False)
-        self.assertTrue(isinstance(l2, set))
-        self.assertFalse(l is l2)
-        self.assertNotEqual(l, l2)
-        self.assertEqual(set(["", "123"]), l2)
-        l = set(["", b"123", u"321"])
-        l2 = cpt.to_text(l, inplace=False)
-        self.assertTrue(isinstance(l2, set))
-        self.assertFalse(l is l2)
-        self.assertNotEqual(l, l2)
-        self.assertEqual(set(["", "123", "321"]), l2)
-
-        # check set types, inplace
-        l = set("")
-        l2 = cpt.to_text(l, inplace=True)
-        self.assertTrue(isinstance(l2, set))
-        self.assertTrue(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual(set(""), l2)
-        l = set([b"", b"123"])
-        l2 = cpt.to_text(l, inplace=True)
-        self.assertTrue(isinstance(l2, set))
-        self.assertTrue(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual(set(["", "123"]), l2)
-        l = set(["", b"123", u"321"])
-        l2 = cpt.to_text(l, inplace=True)
-        self.assertTrue(isinstance(l2, set))
-        self.assertTrue(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual(set(["", "123", "321"]), l2)
-        for i in l2:
-            self.assertTrue(isinstance(i, str))
-
-        # check dict types, not inplace
-        l = {"": ""}
-        l2 = cpt.to_text(l, inplace=False)
-        self.assertTrue(isinstance(l2, dict))
-        self.assertFalse(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual({"": ""}, l2)
-
-        # check dict types, inplace
-        l = {"": ""}
-        l2 = cpt.to_text(l, inplace=True)
-        self.assertTrue(isinstance(l2, dict))
-        self.assertTrue(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual({"": ""}, l2)
-
-    def test_to_bytes(self):
-        self.assertIsNone(cpt.to_bytes(None))
-
-        self.assertTrue(isinstance(cpt.to_bytes(str("")), bytes))
-        self.assertTrue(isinstance(cpt.to_bytes(str("123")), bytes))
-        self.assertTrue(isinstance(cpt.to_bytes(b""), bytes))
-        self.assertTrue(isinstance(cpt.to_bytes(b""), bytes))
-        self.assertTrue(isinstance(cpt.to_bytes(u""), bytes))
-        self.assertTrue(isinstance(cpt.to_bytes(u""), bytes))
-
-        self.assertEqual(b"", cpt.to_bytes(str("")))
-        self.assertEqual(b"123", cpt.to_bytes(str("123")))
-        self.assertEqual(b"", cpt.to_bytes(b""))
-        self.assertEqual(b"123", cpt.to_bytes(b"123"))
-        self.assertEqual(b"", cpt.to_bytes(u""))
-        self.assertEqual(b"123", cpt.to_bytes(u"123"))
-
-        # check list types, not inplace
-        l = [""]
-        l2 = cpt.to_bytes(l)
-        self.assertTrue(isinstance(l2, list))
-        self.assertFalse(l is l2)
-        self.assertNotEqual(l, l2)
-        self.assertEqual([b""], l2)
-        l = ["", "123"]
-        l2 = cpt.to_bytes(l)
-        self.assertTrue(isinstance(l2, list))
-        self.assertFalse(l is l2)
-        self.assertNotEqual(l, l2)
-        self.assertEqual([b"", b"123"], l2)
-        l = ["", b"123", u"321"]
-        l2 = cpt.to_bytes(l)
-        self.assertTrue(isinstance(l2, list))
-        self.assertFalse(l is l2)
-        self.assertNotEqual(l, l2)
-        self.assertEqual([b"", b"123", b"321"], l2)
-
-        # check list types, inplace
-        l = [""]
-        l2 = cpt.to_bytes(l, inplace=True)
-        self.assertTrue(isinstance(l2, list))
-        self.assertTrue(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual([b""], l2)
-        l = ["", b"123"]
-        l2 = cpt.to_bytes(l, inplace=True)
-        self.assertTrue(isinstance(l2, list))
-        self.assertTrue(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual([b"", b"123"], l2)
-        l = ["", b"123", u"321"]
-        l2 = cpt.to_bytes(l, inplace=True)
-        self.assertTrue(isinstance(l2, list))
-        self.assertTrue(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual([b"", b"123", b"321"], l2)
-        for i in l2:
-            self.assertTrue(isinstance(i, bytes))
-
-        # check set types, not inplace
-        l = set([""])
-        l2 = cpt.to_bytes(l, inplace=False)
-        self.assertTrue(isinstance(l2, set))
-        self.assertFalse(l is l2)
-        self.assertNotEqual(l, l2)
-        self.assertEqual(set([b""]), l2)
-        l = set([u"", u"123"])
-        l2 = cpt.to_bytes(l, inplace=False)
-        self.assertTrue(isinstance(l2, set))
-        self.assertFalse(l is l2)
-        self.assertNotEqual(l, l2)
-        self.assertEqual(set([b"", b"123"]), l2)
-        l = set(["", b"123", u"321"])
-        l2 = cpt.to_bytes(l, inplace=False)
-        self.assertTrue(isinstance(l2, set))
-        self.assertFalse(l is l2)
-        self.assertNotEqual(l, l2)
-        self.assertEqual(set([b"", b"123", b"321"]), l2)
-
-        # check set types, inplace
-        l = set("")
-        l2 = cpt.to_bytes(l, inplace=True)
-        self.assertTrue(isinstance(l2, set))
-        self.assertTrue(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual(set(b""), l2)
-        l = set([u"", u"123"])
-        l2 = cpt.to_bytes(l, inplace=True)
-        self.assertTrue(isinstance(l2, set))
-        self.assertTrue(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual(set([b"", b"123"]), l2)
-        l = set(["", b"123", u"321"])
-        l2 = cpt.to_bytes(l, inplace=True)
-        self.assertTrue(isinstance(l2, set))
-        self.assertTrue(l is l2)
-        self.assertEqual(l, l2)
-        self.assertEqual(set([b"", b"123", b"321"]), l2)
-        for i in l2:
-            self.assertTrue(isinstance(i, bytes))
-
-
-if __name__ == "__main__":
-    unittest.main()