diff --git a/kallithea/lib/vcs/backends/git/changeset.py b/kallithea/lib/vcs/backends/git/changeset.py
--- a/kallithea/lib/vcs/backends/git/changeset.py
+++ b/kallithea/lib/vcs/backends/git/changeset.py
@@ -17,7 +17,7 @@ from kallithea.lib.vcs.utils.lazy import
 
 class GitChangeset(BaseChangeset):
     """
-    Represents state of the repository at single revision.
+    Represents state of the repository at a revision.
     """
 
     def __init__(self, repository, revision):
@@ -243,6 +243,7 @@ class GitChangeset(BaseChangeset):
                 return cs
 
     def diff(self, ignore_whitespace=True, context=3):
+        # Only used to feed diffstat
         rev1 = self.parents[0] if self.parents else self.repository.EMPTY_CHANGESET
         rev2 = self
         return ''.join(self.repository.get_diff(rev1, rev2,
@@ -353,13 +354,16 @@ class GitChangeset(BaseChangeset):
 
         :raise ImproperArchiveTypeError: If given kind is wrong.
         :raise VcsError: If given stream is None
-
         """
         allowed_kinds = settings.ARCHIVE_SPECS.keys()
         if kind not in allowed_kinds:
             raise ImproperArchiveTypeError('Archive kind not supported use one'
                 'of %s' % allowed_kinds)
 
+        if stream is None:
+            raise VCSError('You need to pass in a valid stream for filling'
+                           ' with archival data')
+
         if prefix is None:
             prefix = '%s-%s' % (self.repository.name, self.short_id)
         elif prefix.startswith('/'):
@@ -394,6 +398,12 @@ class GitChangeset(BaseChangeset):
         popen.communicate()
 
     def get_nodes(self, path):
+        """
+        Returns combined ``DirNode`` and ``FileNode`` objects list representing
+        state of changeset at the given ``path``. If node at the given ``path``
+        is not instance of ``DirNode``, ChangesetError would be raised.
+        """
+
         if self._get_kind(path) != NodeKind.DIR:
             raise ChangesetError("Directory does not exist for revision %s at "
                 " '%s'" % (self.revision, path))
@@ -434,6 +444,10 @@ class GitChangeset(BaseChangeset):
         return nodes
 
     def get_node(self, path):
+        """
+        Returns ``Node`` object from the given ``path``. If there is no node at
+        the given ``path``, ``ChangesetError`` would be raised.
+        """
         if isinstance(path, unicode):
             path = path.encode('utf-8')
         path = self._fix_path(path)
@@ -465,7 +479,7 @@ class GitChangeset(BaseChangeset):
                     node._blob = obj
                 else:
                     raise NodeDoesNotExistError("There is no file nor directory "
-                        "at the given path '%s' at revision %s"
+                        "at the given path: '%s' at revision %s"
                         % (path, self.short_id))
             # cache node
             self.nodes[path] = node
diff --git a/kallithea/lib/vcs/backends/hg/changeset.py b/kallithea/lib/vcs/backends/hg/changeset.py
--- a/kallithea/lib/vcs/backends/hg/changeset.py
+++ b/kallithea/lib/vcs/backends/hg/changeset.py
@@ -14,7 +14,7 @@ from kallithea.lib.vcs.utils.paths impor
 
 class MercurialChangeset(BaseChangeset):
     """
-    Represents state of the repository at the single revision.
+    Represents state of the repository at a revision.
     """
 
     def __init__(self, repository, revision):
@@ -202,7 +202,7 @@ class MercurialChangeset(BaseChangeset):
                 return cs
 
     def diff(self):
-        # Only used for feed diffstat
+        # Only used to feed diffstat
         return ''.join(self._ctx.diff())
 
     def _fix_path(self, path):
@@ -316,7 +316,6 @@ class MercurialChangeset(BaseChangeset):
         :raise ImproperArchiveTypeError: If given kind is wrong.
         :raise VcsError: If given stream is None
         """
-
         allowed_kinds = settings.ARCHIVE_SPECS.keys()
         if kind not in allowed_kinds:
             raise ImproperArchiveTypeError('Archive kind not supported use one'
@@ -363,11 +362,9 @@ class MercurialChangeset(BaseChangeset):
             dirnodes.append(SubModuleNode(k, url=loc, changeset=cs,
                                           alias=als))
         nodes = dirnodes + filenodes
-        # cache nodes
         for node in nodes:
             self.nodes[node.path] = node
         nodes.sort()
-
         return nodes
 
     def get_node(self, path):
@@ -375,9 +372,7 @@ class MercurialChangeset(BaseChangeset):
         Returns ``Node`` object from the given ``path``. If there is no node at
         the given ``path``, ``ChangesetError`` would be raised.
         """
-
         path = self._fix_path(path)
-
         if path not in self.nodes:
             if path in self._file_paths:
                 node = FileNode(path, changeset=self)