Use print function

examples/popenpoll.py

@@ -2,28 +2,31 @@
 
 "Monitor multiple hosts using popen()/pmonitor()"
 
+from __future__ import print_function
+
 from mininet.net import Mininet
 from mininet.topo import SingleSwitchTopo
 from mininet.util import pmonitor
 from time import time
 from signal import SIGINT
 
+
 def pmonitorTest( N=3, seconds=10 ):
     "Run pings and monitor multiple hosts using pmonitor"
     topo = SingleSwitchTopo( N )
     net = Mininet( topo )
     net.start()
     hosts = net.hosts
-    print "Starting test..."
+    print( "Starting test..." )
     server = hosts[ 0 ]
     popens = {}
     for h in hosts:
         popens[ h ] = h.popen('ping', server.IP() )
-    print "Monitoring output for", seconds, "seconds"
+    print( "Monitoring output for", seconds, "seconds" )
     endTime = time() + seconds
     for h, line in pmonitor( popens, timeoutms=500 ):
         if h:
-            print '<%s>: %s' % ( h.name, line ),
+            print( '<%s>: %s' % ( h.name, line ) )
         if time() >= endTime:
             for p in popens.values():
                 p.send_signal( SIGINT )