I was following the tutorial https://www.youtube.com/watch?v=E71pb2H4VDQ , however there was an error which was not clear, did anyone solved this error ? It was regarding something like
if t.frameExists('link_base') and t.frameExists('color_ball'): # lookupTransform(target_frame, source_frame, time) -> (position, quaternion) (translation,rotation) = t.lookupTransform("marker","link_base",rospy.Time.now())