@@ -4,7 +4,6 @@
 # This module is part of GitPython and is released under
 # the BSD License: http://www.opensource.org/licenses/bsd-license.php
 
-from typing import Tuple, Union
 from gitdb import IStream
 from git.util import (
     hex_to_bin,
@@ -37,6 +36,11 @@
 from io import BytesIO
 import logging
 
+from typing import List, Tuple, Union, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from git.repo import Repo
+
 log = logging.getLogger('git.objects.commit')
 log.addHandler(logging.NullHandler())
 
@@ -71,7 +75,7 @@ class Commit(base.Object, Iterable, Diffable, Traversable, Serializable):
 
     def __init__(self, repo, binsha, tree=None, author=None, authored_date=None, author_tz_offset=None,
                  committer=None, committed_date=None, committer_tz_offset=None,
-                 message=None, parents: Union[Tuple['Commit', ...], None] = None,
+                 message=None, parents: Union[Tuple['Commit', ...], List['Commit'], None] = None,
                  encoding=None, gpgsig=None):
         """Instantiate a new Commit. All keyword arguments taking None as default will
         be implicitly set on first query.
@@ -135,11 +139,11 @@ def __init__(self, repo, binsha, tree=None, author=None, authored_date=None, aut
             self.gpgsig = gpgsig
 
     @classmethod
-    def _get_intermediate_items(cls, commit: 'Commit') -> Tuple['Commit', ...]:  # type: ignore
-        return commit.parents
+    def _get_intermediate_items(cls, commit: 'Commit') -> Tuple['Commit', ...]:  # type: ignore  ## cos overriding super
+        return tuple(commit.parents)
 
     @classmethod
-    def _calculate_sha_(cls, repo, commit):
+    def _calculate_sha_(cls, repo: 'Repo', commit: 'Commit') -> bytes:
         '''Calculate the sha of a commit.
 
         :param repo: Repo object the commit should be part of
@@ -432,7 +436,7 @@ def create_from_tree(cls, repo, tree, message, parent_commits=None, head=False,
 
     #{ Serializable Implementation
 
-    def _serialize(self, stream):
+    def _serialize(self, stream: BytesIO) -> 'Commit':
         write = stream.write
         write(("tree %s\n" % self.tree).encode('ascii'))
         for p in self.parents:
@@ -473,7 +477,7 @@ def _serialize(self, stream):
         # END handle encoding
         return self
 
-    def _deserialize(self, stream):
+    def _deserialize(self, stream: BytesIO) -> 'Commit':
         """:param from_rev_list: if true, the stream format is coming from the rev-list command
         Otherwise it is assumed to be a plain data stream from our object"""
         readline = stream.readline
@@ -513,7 +517,7 @@ def _deserialize(self, stream):
         buf = enc.strip()
         while buf:
             if buf[0:10] == b"encoding ":
-                self.encoding = buf[buf.find(' ') + 1:].decode(
+                self.encoding = buf[buf.find(b' ') + 1:].decode(
                     self.encoding, 'ignore')
             elif buf[0:7] == b"gpgsig ":
                 sig = buf[buf.find(b' ') + 1:] + b"\n"
 
@@ -3,7 +3,6 @@
 #
 # This module is part of GitPython and is released under
 # the BSD License: http://www.opensource.org/licenses/bsd-license.php
-from typing import Iterable, Iterator, Tuple, Union, cast
 from git.util import join_path
 import git.diff as diff
 from git.util import to_bin_sha
@@ -18,6 +17,17 @@
     tree_to_stream
 )
 
+
+# typing -------------------------------------------------
+
+from typing import Iterable, Iterator, Tuple, Union, cast, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from io import BytesIO
+
+#--------------------------------------------------------
+
+
 cmp = lambda a, b: (a > b) - (a < b)
 
 __all__ = ("TreeModifier", "Tree")
@@ -321,15 +331,15 @@ def __contains__(self, item):
     def __reversed__(self):
         return reversed(self._iter_convert_to_object(self._cache))
 
-    def _serialize(self, stream):
+    def _serialize(self, stream: 'BytesIO') -> 'Tree':
         """Serialize this tree into the stream. Please note that we will assume
         our tree data to be in a sorted state. If this is not the case, serialization
         will not generate a correct tree representation as these are assumed to be sorted
         by algorithms"""
         tree_to_stream(self._cache, stream.write)
         return self
 
-    def _deserialize(self, stream):
+    def _deserialize(self, stream: 'BytesIO') -> 'Tree':
         self._cache = tree_entries_from_data(stream.read())
         return self
 
 
@@ -5,7 +5,6 @@
 # the BSD License: http://www.opensource.org/licenses/bsd-license.php
 """Module for general utility functions"""
 
-
 from git.util import (
     IterableList,
     Actor
@@ -20,9 +19,10 @@
 from datetime import datetime, timedelta, tzinfo
 
 # typing ------------------------------------------------------------
-from typing import Any, Callable, Deque, IO, Iterator, Sequence, TYPE_CHECKING, Tuple, Type, Union, cast, overload
+from typing import (Any, Callable, Deque, IO, Iterator, Sequence, TYPE_CHECKING, Tuple, Type, Union, cast, overload)
 
 if TYPE_CHECKING:
+    from io import BytesIO
     from .submodule.base import Submodule
     from .commit import Commit
     from .blob import Blob
@@ -412,14 +412,14 @@ class Serializable(object):
     """Defines methods to serialize and deserialize objects from and into a data stream"""
     __slots__ = ()
 
-    def _serialize(self, stream):
+    def _serialize(self, stream: 'BytesIO') -> 'Serializable':
         """Serialize the data of this object into the given data stream
         :note: a serialized object would ``_deserialize`` into the same object
         :param stream: a file-like object
         :return: self"""
         raise NotImplementedError("To be implemented in subclass")
 
-    def _deserialize(self, stream):
+    def _deserialize(self, stream: 'BytesIO') -> 'Serializable':
         """Deserialize all information regarding this object from the stream
         :param stream: a file-like object
         :return: self"""