diff --git a/paddle/fluid/framework/op_desc.cc b/paddle/fluid/framework/op_desc.cc
index c473b1129227c4173285b5f34ef18319ed6f9f56..984ea3a3dd60e1fbd1612467b478ea1aa4718afb 100644
--- a/paddle/fluid/framework/op_desc.cc
+++ b/paddle/fluid/framework/op_desc.cc
@@ -202,7 +202,6 @@ std::vector<std::string> OpDesc::AttrNames() const {
 }
 
 void OpDesc::SetAttr(const std::string &name, const Attribute &v) {
-  VLOG(11) << "SetAttr: " << Type() << ", " << name << ", " << v.which();
   // NOTICE(minqiyang): pybind11 will take the empty list in python as
   // the std::vector<int> type in C++; so we have to change the attr's type
   // here if we meet this issue
diff --git a/python/paddle/fluid/compat.py b/python/paddle/fluid/compat.py
index 32f567253e0280c4f3af50f75fdd6f775186fe64..16932a2a0ca5c5a16489b59b26d1b6ff058a1de2 100644
--- a/python/paddle/fluid/compat.py
+++ b/python/paddle/fluid/compat.py
@@ -15,18 +15,77 @@
 import six
 import math
 
+__all__ = [
+    'to_literal_str',
+    'to_bytes',
+    'round',
+    'floor_division',
+    'get_exception_message',
+]
 
 #  str and bytes related functions
-def to_literal_str(obj, encoding='utf-8'):
+def to_literal_str(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
+    """
+    if obj is None:
+        return obj
+
     if isinstance(obj, list):
-        return [_to_literal_str(item, encoding) for item in obj]
+        if inplace:
+            for i in six.moves.xrange(len(obj)):
+                obj[i] = _to_literal_str(obj[i], encoding)
+            return obj
+        else:
+            return [_to_literal_str(item, encoding) for item in obj]
     elif isinstance(obj, set):
-        return set([_to_literal_str(item, encoding) for item in obj])
+        if inplace:
+            for item in obj:
+                obj.remove(item)
+                obj.add(_to_literal_str(item, encoding))
+            return obj
+        else:
+            return set([_to_literal_str(item, encoding) for item in obj])
     else:
         return _to_literal_str(obj, encoding)
 
 
 def _to_literal_str(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):
@@ -35,16 +94,70 @@ def _to_literal_str(obj, encoding):
         return six.u(obj)
 
 
-def to_bytes(obj, encoding='utf-8'):
+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
+    """
+    if obj is None:
+        return obj
+
     if isinstance(obj, list):
-        return [_to_bytes(item, encoding) for item in obj]
+        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):
-        return set([_to_bytes(item, encoding) for item in obj])
+        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):
@@ -64,15 +177,48 @@ def round(x, d=0):
     Returns:
         round result of x
     """
-    p = 10**d
-    return float(math.floor((x * p) + math.copysign(0.5, x))) / p
+    if six.PY3:
+        # The official walkaround of round in Python3 is incorrect
+        # we implement accroding this answer: https://www.techforgeek.info/round_python.html
+        if x > 0.0:
+            p = 10 ** d
+            return float(math.floor((x * p) + math.copysign(0.5, x))) / p
+        else:
+            p = 10 ** d
+            return float(math.ceil((x * p) + math.copysign(0.5, x))) / p
+    else:
+        import __builtin__
+        return __builtin__.round(x, d)
 
 
 def floor_division(x, y):
+    """
+    Compatible division which act the same behaviour in Python3 and Python2,
+    whose result will be a int value of floor(x / y) in Python3 and value of
+    (x / y) in Python2.
+
+    Args:
+        x(int|float) : The number to divide.
+        y(int|float) : The number to be divided
+
+    Returns:
+        division result of x // y
+    """
     return x // y
 
 # exception related functions
 def get_exception_message(exc):
+    """
+    Get the error message of a specific exception
+
+    Args:
+        exec(Exception) : The exception to get error message.
+
+    Returns:
+        the error message of exec
+    """
+    assert exc is not None
+
     if six.PY2:
         return exc.message
     else:
diff --git a/python/paddle/fluid/layers/detection.py b/python/paddle/fluid/layers/detection.py
index c11455b7a6ecf467e64ad20a9499623114c09de3..e21a7a3ddd0b6ad9e21d4a895f0dd37f8b696f05 100644
--- a/python/paddle/fluid/layers/detection.py
+++ b/python/paddle/fluid/layers/detection.py
@@ -20,6 +20,7 @@ from .layer_function_generator import autodoc, templatedoc
 from ..layer_helper import LayerHelper
 from . import tensor
 from . import nn
+from .. import compat as cpt
 import math
 import six
 from functools import reduce
@@ -1104,7 +1105,8 @@ def multi_box_head(inputs,
         mbox_loc = nn.transpose(mbox_loc, perm=[0, 2, 3, 1])
         new_shape = [
             mbox_loc.shape[0],
-            mbox_loc.shape[1] * mbox_loc.shape[2] * mbox_loc.shape[3] / 4, 4
+            mbox_loc.shape[1] * mbox_loc.shape[2] * cpt.floor_division(mbox_loc.shape[3], 4),
+            4
         ]
         mbox_loc_flatten = nn.reshape(mbox_loc, shape=new_shape)
         mbox_locs.append(mbox_loc_flatten)
@@ -1119,8 +1121,9 @@ def multi_box_head(inputs,
             stride=stride)
         conf_loc = nn.transpose(conf_loc, perm=[0, 2, 3, 1])
         new_shape = [
-            conf_loc.shape[0], conf_loc.shape[1] * conf_loc.shape[2] *
-            conf_loc.shape[3] / num_classes, num_classes
+            conf_loc.shape[0],
+            conf_loc.shape[1] * conf_loc.shape[2] * cpt.floor_division(conf_loc.shape[3], num_classes),
+            num_classes
         ]
         conf_loc_flatten = nn.reshape(conf_loc, shape=new_shape)
         mbox_confs.append(conf_loc_flatten)
diff --git a/python/paddle/fluid/tests/unittests/test_compat.py b/python/paddle/fluid/tests/unittests/test_compat.py
new file mode 100644
index 0000000000000000000000000000000000000000..0725d2c49aa55f53ef9f9e484b6e35d48288b2d9
--- /dev/null
+++ b/python/paddle/fluid/tests/unittests/test_compat.py
@@ -0,0 +1,490 @@
+#   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.fluid.compat as cpt
+import six
+
+
+class TestCompatible(unittest.TestCase):
+    def test_to_literal_str(self):
+        # Only support python2.x and python3.x now
+        self.assertTrue(six.PY2 | six.PY3)
+
+        if six.PY2:
+            # check None
+            self.assertIsNone(cpt.to_literal_str(None))
+
+            # check all string related types
+            self.assertTrue(isinstance(cpt.to_literal_str(str("")), unicode))
+            self.assertTrue(isinstance(cpt.to_literal_str(str("123")), unicode))
+            self.assertTrue(isinstance(cpt.to_literal_str(b""), unicode))
+            self.assertTrue(isinstance(cpt.to_literal_str(b""), unicode))
+            self.assertTrue(isinstance(cpt.to_literal_str(u""), unicode))
+            self.assertTrue(isinstance(cpt.to_literal_str(u""), unicode))
+
+            self.assertEqual(u"", cpt.to_literal_str(str("")))
+            self.assertEqual(u"123", cpt.to_literal_str(str("123")))
+            self.assertEqual(u"", cpt.to_literal_str(b""))
+            self.assertEqual(u"123", cpt.to_literal_str(b"123"))
+            self.assertEqual(u"", cpt.to_literal_str(u""))
+            self.assertEqual(u"123", cpt.to_literal_str(u"123"))
+
+            # check list types, not inplace
+            l = [""]
+            l2 = cpt.to_literal_str(l)
+            self.assertTrue(isinstance(l2, list))
+            self.assertFalse(l is l2)
+            self.assertEqual(l, l2)
+            self.assertEqual([u""], l2)
+            l = ["", "123"]
+            l2 = cpt.to_literal_str(l)
+            self.assertTrue(isinstance(l2, list))
+            self.assertFalse(l is l2)
+            self.assertEqual(l, l2)
+            self.assertEqual([u"", u"123"], l2)
+            l = ["", b'123', u"321"]
+            l2 = cpt.to_literal_str(l)
+            self.assertTrue(isinstance(l2, list))
+            self.assertFalse(l is l2)
+            self.assertEqual(l, l2)
+            self.assertEqual([u"", u"123", u"321"], l2)
+            for i in l2:
+                self.assertTrue(isinstance(i, unicode))
+
+
+            # check list types, inplace
+            l = [""]
+            l2 = cpt.to_literal_str(l, inplace=True)
+            self.assertTrue(isinstance(l2, list))
+            self.assertTrue(l is l2)
+            self.assertEqual(l, l2)
+            self.assertEqual([u""], l2)
+            l = ["", "123"]
+            l2 = cpt.to_literal_str(l, inplace=True)
+            self.assertTrue(isinstance(l2, list))
+            self.assertTrue(l is l2)
+            self.assertEqual(l, l2)
+            self.assertEqual([u"", u"123"], l2)
+            l = ["", b"123", u"321"]
+            l2 = cpt.to_literal_str(l, inplace=True)
+            self.assertTrue(isinstance(l2, list))
+            self.assertTrue(l is l2)
+            self.assertEqual(l, l2)
+            self.assertEqual([u"", u"123", u"321"], l2)
+
+            # check set types, not inplace
+            l = set("")
+            l2 = cpt.to_literal_str(l, inplace=False)
+            self.assertTrue(isinstance(l2, set))
+            self.assertFalse(l is l2)
+            self.assertEqual(l, l2)
+            self.assertEqual(set(u""), l2)
+            l = set([b"", b"123"])
+            l2 = cpt.to_literal_str(l, inplace=False)
+            self.assertTrue(isinstance(l2, set))
+            self.assertFalse(l is l2)
+            self.assertEqual(l, l2)
+            self.assertEqual(set([u"", u"123"]), l2)
+            l = set(["", b"123", u"321"])
+            l2 = cpt.to_literal_str(l, inplace=False)
+            self.assertTrue(isinstance(l2, set))
+            self.assertFalse(l is l2)
+            self.assertEqual(l, l2)
+            self.assertEqual(set([u"", u"123", u"321"]), l2)
+            for i in l2:
+                self.assertTrue(isinstance(i, unicode))
+
+            # check set types, inplace
+            l = set("")
+            l2 = cpt.to_literal_str(l, inplace=True)
+            self.assertTrue(isinstance(l2, set))
+            self.assertTrue(l is l2)
+            self.assertEqual(l, l2)
+            self.assertEqual(set(u""), l2)
+            l = set([b"", b"123"])
+            l2 = cpt.to_literal_str(l, inplace=True)
+            self.assertTrue(isinstance(l2, set))
+            self.assertTrue(l is l2)
+            self.assertEqual(l, l2)
+            self.assertEqual(set([u"", u"123"]), l2)
+            l = set(["", b"123", u"321"])
+            l2 = cpt.to_literal_str(l, inplace=True)
+            self.assertTrue(isinstance(l2, set))
+            self.assertTrue(l is l2)
+            self.assertEqual(l, l2)
+            self.assertEqual(set([u"", u"123", u"321"]), l2)
+
+        elif six.PY3:
+            self.assertIsNone(cpt.to_literal_str(None))
+
+            self.assertTrue(isinstance(cpt.to_literal_str(str("")), str))
+            self.assertTrue(isinstance(cpt.to_literal_str(str("123")), str))
+            self.assertTrue(isinstance(cpt.to_literal_str(b""), str))
+            self.assertTrue(isinstance(cpt.to_literal_str(b""), str))
+            self.assertTrue(isinstance(cpt.to_literal_str(u""), str))
+            self.assertTrue(isinstance(cpt.to_literal_str(u""), str))
+
+            self.assertEqual("", cpt.to_literal_str(str("")))
+            self.assertEqual("123", cpt.to_literal_str(str("123")))
+            self.assertEqual("", cpt.to_literal_str(b""))
+            self.assertEqual("123", cpt.to_literal_str(b"123"))
+            self.assertEqual("", cpt.to_literal_str(u""))
+            self.assertEqual("123", cpt.to_literal_str(u"123"))
+
+            # check list types, not inplace
+            l = [""]
+            l2 = cpt.to_literal_str(l)
+            self.assertTrue(isinstance(l2, list))
+            self.assertFalse(l is l2)
+            self.assertEqual(l, l2)
+            self.assertEqual([""], l2)
+            l = ["", "123"]
+            l2 = cpt.to_literal_str(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_literal_str(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_literal_str(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_literal_str(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_literal_str(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_literal_str(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_literal_str(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_literal_str(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_literal_str(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_literal_str(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_literal_str(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))
+
+    def test_to_bytes(self):
+        # Only support python2.x and python3.x now
+        self.assertTrue(six.PY2 | six.PY3)
+
+        if six.PY2:
+            # check None
+            self.assertIsNone(cpt.to_bytes(None))
+
+            # check all string related types
+            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.assertEqual(l, l2)
+            self.assertEqual([b""], l2)
+            l = ["", "123"]
+            l2 = cpt.to_bytes(l)
+            self.assertTrue(isinstance(l2, list))
+            self.assertFalse(l is l2)
+            self.assertEqual(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.assertEqual(l, l2)
+            self.assertEqual([b"", b"123", b"321"], l2)
+            for i in l2:
+                self.assertTrue(isinstance(i, bytes))
+
+
+            # 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 = ["", "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)
+
+            # 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.assertEqual(l, l2)
+            self.assertEqual(set(b""), l2)
+            l = set([b"", b"123"])
+            l2 = cpt.to_bytes(l, inplace=False)
+            self.assertTrue(isinstance(l2, set))
+            self.assertFalse(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=False)
+            self.assertTrue(isinstance(l2, set))
+            self.assertFalse(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))
+
+            # 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([b"", b"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)
+
+        elif six.PY3:
+            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))
+
+    def test_round(self):
+        self.assertEqual(3.0, cpt.round(3.4))
+        self.assertEqual(4.0, cpt.round(3.5))
+        self.assertEqual(0.0, cpt.round(0.1))
+        self.assertEqual(-0.0, cpt.round(-0.1))
+        self.assertEqual(-3.0, cpt.round(-3.4))
+        self.assertEqual(-4.0, cpt.round(-3.5))
+        self.assertEqual(5.0, cpt.round(5))
+        self.assertRaises(TypeError, cpt.round, None)
+
+    def test_floor_division(self):
+        self.assertEqual(0.0, cpt.floor_division(3, 4))
+        self.assertEqual(1.0, cpt.floor_division(4, 3))
+        self.assertEqual(2.0, cpt.floor_division(6, 3))
+        self.assertEqual(-2.0, cpt.floor_division(-4, 3))
+        self.assertEqual(-2.0, cpt.floor_division(-6, 3))
+        self.assertRaises(ZeroDivisionError, cpt.floor_division, 3, 0)
+        self.assertRaises(TypeError, cpt.floor_division, None, None)
+
+    def test_get_exception_message(self):
+        exception_message = "test_message"
+        self.assertRaises(AssertionError, cpt.get_exception_message, None)
+        if six.PY2:
+            self.assertRaises(AttributeError, cpt.get_exception_message, exception_message)
+            try:
+                raise RuntimeError(exception_message)
+            except Exception as e:
+                self.assertEqual(exception_message, cpt.get_exception_message(e))
+                self.assertIsNotNone(e)
+
+            try:
+                raise Exception(exception_message)
+            except Exception as e:
+                self.assertEqual(exception_message, cpt.get_exception_message(e))
+                self.assertIsNotNone(e)
+
+        if six.PY3:
+            try:
+                raise RuntimeError(exception_message)
+            except Exception as e:
+                self.assertEqual(exception_message, cpt.get_exception_message(e))
+                self.assertIsNotNone(e)
+
+            try:
+                raise Exception(exception_message)
+            except Exception as e:
+                self.assertEqual(exception_message, cpt.get_exception_message(e))
+                self.assertIsNotNone(e)
+
+
+if __name__ == "__main__":
+    unittest.main()