I'm working through Python Programming by Zelle. I've entered the code for the racquetball problem in Chapter 9 exactly as written in the text. (At least I think so.) The program returns one game only then quits. I've prototyped and unit tested but can't find my mistake. Any insights would be helpful. Here is my code:

```
From random import random
def main():
#print and introduction
printIntro()
#get the inputs: probA, probB,n
probA,probB,n=getInputs()
#simulate n games of racquetball using probA and probB
winsA, winsB=simNGames(n,probA,probB)
#print a report on the wins for playerA and playerB
printSummary(winsA,winsB)
def printIntro():
print("This program simulates a game of racquetball between two")
print("players called A and B. The abilities of each player are")
print("indicated by a probability(a number between 0 and 1) that")
print("the player wins the point when serving. Player A always")
print("has the first serve.")
def getInputs():
#returns the three simulation parameters, probA, probB and n
a=eval(input("What is the probability playerA wins a serve? "))
b=eval(input("What is the probability playerB wins a serve? "))
n=eval(input("How many games do you want to simulate? "))
return a,b,n
def simNGames(n,probA, probB):
#Initialize winsA and winsB to 0
winsA=winsB=0
#loop n times
for i in range(n):
#simulate a game
scoreA, scoreB=simOneGame(probA, probB)
#if playerA wins
if scoreA>scoreB:
#Add one to wins A
winsA=winsA+1
#else
else:
winsB=winsB+1
return winsA, winsB
def simOneGame(probA, probB):
#initialize scores to 0
serving="A"
scoreA=0
scoreB=0
#set serving to A
#Loop while the game is not over:
while not gameOver(scoreA,scoreB):
if serving=="A":
if random()<probA:
scoreA=scoreA+1
else:
serving="B"
else:
if random()<probB:
scoreB=scoreB+1
else:
serving="A"
return scoreA, scoreB
def gameOver(a,b):
#a and b represent scores for a racquetball game
#Returns True if the game is over, False otherwise.
return a==15 or b==15
def printSummary(winsA,winsB):
#prints a summary of wins for each player
n=winsA+winsB
print("\nGames simulated:", n)
print("Wins for A: {0} ({1:0.1%})".format(winsA, winsA/n))
print("Wins for B: {0} ({1:0.1%})".format(winsB,winsB/n))
```