Pass code check with pylint=2.4.4 (#1012)

examples/controllers.py

@@ -26,6 +26,7 @@ class MultiSwitch( OVSSwitch ):
     def start( self, controllers ):
         return OVSSwitch.start( self, [ cmap[ self.name ] ] )
 
+
 topo = TreeTopo( depth=2, fanout=2 )
 net = Mininet( topo=topo, switch=MultiSwitch, build=False, waitConnected=True )
 for c in [ c0, c1 ]: