Fix undefined sleep()

mininet/clean.py

@@ -16,6 +16,7 @@ import time
 from mininet.log import info
 from mininet.term import cleanUpScreens
 
+
 def sh( cmd ):
     "Print a command and send it to the shell"
     info( cmd + '\n' )
@@ -32,7 +33,7 @@ def killprocs( pattern ):
             pids = ''
         if pids:
             sh( 'pkill -f 9 mininet:' )
-            sleep( .5 )
+            time.sleep( .5 )
         else:
             break