Error in running OpenAI Cartpole in Noetic

Running the following command roslaunch cartpole_v0_training start_training.launch terminates with the following error. This is most probably a python2 → pytthon3 error or import issue. Can this be fixed in the course.

Traceback (most recent call last):
  File "/home/simulations/public_sim_ws/src/all/cart_pole/cartpole_v0_training/scripts/", line 118, in <module>
    rospy.loginfo("Best 100 score: {:0.2f}".format(reduce(lambda x, y: x + y, l[-100:]) / len(l[-100:])))
NameError: name 'reduce' is not defined

Hi, could you tell us in which unit this happens, because in unit 0 it works ok.