Rock-paper-scissors-lizard-Spock

import random
import math

# 0 - rock
# 1 - Spock
# 2 - paper
# 3 - lizard
# 4 - scissors

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:
        return "You have entered an invalid choice."

def number_to_name(number):
   
    if number==0:
        return "rock"
    elif number==1:
        return "Spock"
    elif number==2:
        return "paper"
    elif number==3:
        return "lizard"
    elif number==4:
        return "scissors"
    else:
        return "You have entered an invalid choice."

def rpsls(player_choice): 
    
    print "Player chooses",player_choice
    player_number=name_to_number(player_choice)
    
    comp_number=random.randrange(0,5)
    comp_choice=number_to_name(comp_number)
    print "Computer chooses",comp_choice 
    
    diff_choices=(comp_number-player_number)%5
    if diff_choices==1 or diff_choices==2:
        print "Computer wins!\n"
    elif diff_choices==3 or diff_choices==4:
        print "Player wins!\n"
    else:
        print "Player and computer tie!\n"
 
rpsls("rock")
rpsls("Spock")
rpsls("paper")
rpsls("lizard")
rpsls("scissors")