python エラー

difference=((Cmpnum-Playernum)%5)がエラーになってしまいます、ご指摘よろしくお願いします。

コード
# Rock-paper-scissors-lizard-Spock template


# The key idea of this program is to equate the strings
# "rock", "paper", "scissors", "lizard", "Spock" to numbers
# as follows:
#
# 0 - rock
# 1 - Spock
# 2 - paper
# 3 - lizard
# 4 - scissors

# helper functions
import random

def name_to_number(name):
    if name==rock:
        return 0
    elif name==Spock:
        return 1
    elif name==paper:
        return 2
    elif name==lizard:
        return 3
    elif name==scissors:
        return 4
    else:
        print("its not appropriate name")

    # delete the following pass statement and fill in your code below


    # convert name to number using if/elif/else
    # don't forget to return the result!


def number_to_name(number):
    # delete the following pass statement and fill in your code below
    if number==0:
        return rock
    if number==1:
        return Spock
    if number==2:
        return lizard
    if number==3:
        return scissors
    else:
        print("its not appropriate number")

    # convert number to a name using if/elif/else
    # don't forget to return the result!


def rpsls(player_choice):
    # delete the following pass statement and fill in your code below


    # print a blank line to separate consecutive games
    print("________________________________")
    # print out the message for the player's choice
    print("player_choice")
    # convert the player's choice to player_number using the function name_to_number()
    Playernum=name_to_number(player_choise)
    # compute random guess for comp_number using random.randrange()
    Cmpnum=random.randrange(0,4)
    # convert comp_number to comp_choice using the function number_to_name()
    CmpChoice=number_to_name(rn)
    # print out the message for computer's choice
    print("Computer's choise is{0}".format(CmpChoise)
    # compute difference of comp_number and player_number modulo five
    difference=((Cmpnum-Playernum)%5)
    # use if/elif/else to determine winner, print winner message
  

# test your code - THESE CALLS MUST BE PRESENT IN YOUR SUBMITTED CODE
rpsls("rock")
rpsls("Spock")
rpsls("paper")
rpsls("lizard")
rpsls("scissors")

# always remember to check your completed program against the grading rubric