Fix code minor code check errors

examples/clustercli.py

@@ -30,12 +30,14 @@ class ClusterCLI( CLI ):
         global nx, plt
         if not nx:
             try:
+                # pylint: disable=import-error
                 import networkx
                 nx = networkx  # satisfy pylint
                 from matplotlib import pyplot
                 plt = pyplot   # satisfiy pylint
                 import pygraphviz
                 assert pygraphviz  # silence pyflakes
+                # pylint: enable=import-error
             except ImportError:
                 error( 'plot requires networkx, matplotlib and pygraphviz - '
                        'please install them and try again\n' )

mininet/node.py

@@ -52,7 +52,6 @@ import re
 import signal
 import select
 from subprocess import Popen, PIPE
-from operator import or_
 from time import sleep
 
 from mininet.log import info, error, warn, debug
@@ -1130,11 +1129,12 @@ class OVSSwitch( Switch ):
            update: update cached value"""
         if not self._uuids or update:
             controllers = self.cmd( 'ovs-vsctl -- get Bridge', self,
-                                   'Controller' ).strip()
+                                    'Controller' ).strip()
             if controllers.startswith( '[' ) and controllers.endswith( ']' ):
                 controllers = controllers[ 1 : -1 ]
                 if controllers:
-                    self._uuids = [ c.strip() for c in controllers.split( ',' ) ]
+                    self._uuids = [ c.strip()
+                                    for c in controllers.split( ',' ) ]
         return self._uuids
 
     def connected( self ):