Creating a Subscriber in python

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Hi!

I’m trying to create a subscriber using python for this package, following the tutorials that ros provide. The package already contains a subscriber in c++. It uses geometry_msgs/Twist.h

I just want to publish in terminal the values from x, y, width and height. However when I run the code I receive nothing.

This is the code that Im using

 #!/usr/bin/env python
 import rospy
 from geometry_msgs.msg import Twist

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

 def listener():

# In ROS, nodes are uniquely named. If two nodes with the same
# node are launched, the previous one is kicked off. The
# anonymous=True flag means that rospy will choose a unique
# name for our 'listener' node so that multiple listeners can
# run simultaneously.
    rospy.init_node('listener', anonymous=True)

    rospy.Subscriber("commands", Twist, callback)

  # spin() simply keeps python from exiting until this node is stopped
    rospy.spin()

 if __name__ == '__main__':
      listener()

Hope you could give me a hand thanks