@@ -22,7 +22,6 @@
 from itertools import chain
 from functools import reduce
 
-import sys
 
 
 __all__ = ('ObjectDBR', 'ObjectDBW', 'FileDBBase', 'CompoundDB', 'CachingDB')
@@ -206,7 +205,6 @@ def _databases_recursive(database, output):
     """Fill output list with database from db, in order. Deals with Loose, Packed
     and compound databases."""
     if isinstance(database, CompoundDB):
-        compounds = list()
         dbs = database.databases()
         output.extend(db for db in dbs if not isinstance(db, CompoundDB))
         for cdb in (db for db in dbs if isinstance(db, CompoundDB)):
 
@@ -12,12 +12,7 @@
 from gitdb.db.pack import PackedDB
 from gitdb.db.ref import ReferenceDB
 
-from gitdb.util import LazyMixin
-from gitdb.exc import (
-    InvalidDBRoot,
-    BadObject,
-    AmbiguousObjectName
-)
+from gitdb.exc import InvalidDBRoot
 
 import os
 
 
@@ -10,7 +10,6 @@
 
 
 from gitdb.exc import (
-    InvalidDBRoot,
     BadObject,
     AmbiguousObjectName
 )
@@ -55,8 +54,6 @@
 from gitdb.utils.encoding import force_bytes
 
 import tempfile
-import mmap
-import sys
 import os
 
 
@@ -149,11 +146,6 @@ def _map_loose_object(self, sha):
                 raise BadObject(sha)
             # END handle error
         # END exception handling
-        try:
-            return mmap.mmap(fd, 0, access=mmap.ACCESS_READ)
-        finally:
-            os.close(fd)
-        # END assure file is closed
 
     def set_ostream(self, stream):
         """:raise TypeError: if the stream does not support the Sha1Writer interface"""
 
@@ -103,7 +103,6 @@ def stream(self, sha):
         return entity.stream_at_index(index)
 
     def sha_iter(self):
-        sha_list = list()
         for entity in self.entities():
             index = entity.index()
             sha_by_index = index.sha
 
@@ -6,7 +6,6 @@
     CompoundDB,
 )
 
-import os
 __all__ = ('ReferenceDB', )
 
 class ReferenceDB(CompoundDB):
 
@@ -6,18 +6,15 @@
 Keeping this code separate from the beginning makes it easier to out-source
 it into c later, if required"""
 
-from gitdb.exc import (
-    BadObjectType
-)
-
 import zlib
 from gitdb.util import byte_ord
 decompressobj = zlib.decompressobj
 
 import mmap
 from itertools import islice
+from functools import reduce
 
-from gitdb.utils.compat import izip
+from gitdb.utils.compat import izip, buffer, xrange
 from gitdb.typ import (
     str_blob_type,
     str_commit_type,
@@ -247,7 +244,6 @@ def compress(self):
         if slen < 2:
             return self
         i = 0
-        slen_orig = slen
 
         first_data_index = None
         while i < slen:
@@ -399,7 +395,6 @@ def loose_object_header_info(m):
         object as well as its uncompressed size in bytes.
     :param m: memory map from which to read the compressed object data"""
     from gitdb.const import NULL_BYTE
-    from gitdb.utils.encoding import force_text
 
     decompress_size = 8192      # is used in cgit as well
     hdr = decompressobj().decompress(m, decompress_size)
@@ -684,7 +679,7 @@ def is_equal_canonical_sha(canonical_length, match, sha1):
 
 
 try:
-    # raise ImportError; # DEBUG
+    # NOQA
     from _perf import connect_deltas
 except ImportError:
     pass
@@ -7,6 +7,7 @@
 
 from gitdb.exc import (
     BadObject,
+    AmbiguousObjectName,
     UnsupportedOperation,
     ParseError
 )
@@ -57,11 +58,7 @@
     FlexibleSha1Writer
 )
 
-from struct import (
-    pack,
-    unpack,
-)
-
+from struct import pack
 from binascii import crc32
 
 from gitdb.const import NULL_BYTE
 
@@ -3,9 +3,8 @@
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 
-from io import BytesIO, StringIO
+from io import BytesIO
 
-import errno
 import mmap
 import os
 import zlib
@@ -15,7 +14,6 @@
     stream_copy,
     apply_delta_data,
     connect_deltas,
-    DeltaChunkList,
     delta_types
 )
 
 
@@ -6,12 +6,16 @@
 from gitdb.test.lib import (
     with_rw_directory,
     with_packs_rw,
-    ZippedStoreShaWriter,
     fixture_path,
     TestBase
 )
 
-from gitdb.stream import Sha1Writer
+
+
+from gitdb.stream import (
+    Sha1Writer,
+    ZippedStoreShaWriter
+)
 
 from gitdb.base import (
     IStream,
Original file line number	Diff line number	Diff line change
@@ -6,7 +6,6 @@
6	6	CompoundDB,
7	7	)
8	8
9		- import os
10	9	__all__ = ('ReferenceDB', )
11	10
12	11	class ReferenceDB(CompoundDB):