No need to assign the results of expressions used only for side effects.

Lib/UserDict.py

@@ -98,7 +98,7 @@ class DictMixin:
             yield k
     def has_key(self, key):
         try:
-            value = self[key]
+            self[key]
         except KeyError:
             return False
         return True

Lib/genericpath.py

@@ -15,7 +15,7 @@ __all__ = ['commonprefix', 'exists', 'getatime', 'getctime', 'getmtime',
 def exists(path):
     """Test whether a path exists.  Returns False for broken symbolic links"""
     try:
-        st = os.stat(path)
+        os.stat(path)
     except os.error:
         return False
     return True

Lib/mimetypes.py

@@ -546,7 +546,6 @@ _default_mime_types()
 
 
 if __name__ == '__main__':
-    import sys
     import getopt
 
     USAGE = """\

Lib/posixpath.py

@@ -139,7 +139,7 @@ def islink(path):
 def lexists(path):
     """Test whether a path exists.  Returns True for broken symbolic links"""
     try:
-        st = os.lstat(path)
+        os.lstat(path)
     except os.error:
         return False
     return True

Lib/rexec.py

@@ -244,7 +244,7 @@ class RExec(ihooks._Verbose):
         m.open = m.file = self.r_open
 
     def make_main(self):
-        m = self.add_module('__main__')
+        self.add_module('__main__')
 
     def make_osname(self):
         osname = os.name

Lib/subprocess.py

@@ -920,7 +920,7 @@ class Popen(object):
             """Wait for child process to terminate.  Returns returncode
             attribute."""
             if self.returncode is None:
-                obj = WaitForSingleObject(self._handle, INFINITE)
+                WaitForSingleObject(self._handle, INFINITE)
                 self.returncode = GetExitCodeProcess(self._handle)
             return self.returncode
 

Lib/threading.py

@@ -10,7 +10,6 @@ except ImportError:
 
 import warnings
 
-from functools import wraps
 from time import time as _time, sleep as _sleep
 from traceback import format_exc as _format_exc
 from collections import deque

Lib/urllib.py

@@ -234,7 +234,7 @@ class URLopener:
                 hdrs = fp.info()
                 fp.close()
                 return url2pathname(splithost(url1)[1]), hdrs
-            except IOError, msg:
+            except IOError:
                 pass
         fp = self.open(url, data)
         try:
@@ -1277,7 +1277,7 @@ def urlencode(query,doseq=0):
             else:
                 try:
                     # is this a sufficient test for sequence-ness?
-                    x = len(v)
+                    len(v)
                 except TypeError:
                     # not a sequence
                     v = quote_plus(str(v))