listener.py

#!/usr/bin/env python
import roslib; roslib.load_manifest('beginner_tutorials')
import rospy
from std_msgs.msg import String

def callback(data):
        rospy.loginfo(rospy.get_name()+"I heard %s", data.data)

def listener():
        rospy.init_node('listener', anonymous=True)
        rospy.Subscriber("chatter", String, callback)
        rospy.spin()
if __name__=='__main__':
        listener()