x2

# Wait for the transform to become available
listener.waitForTransform('/base_link', '/end_effector', rospy.Time(), rospy.Duration(4.0))

# Get the transformation matrix from the robot base to the end effector
(trans, rot) = listener.lookupTransform('/base_link', '/end_effector', rospy.Time(0))

rot_matrix = tf.transformations.quaternion_matrix(rot)

transformation_matrix = tf.transformations.concatenate_matrices(rot_matrix, tf.transformations.translation_matrix(trans))