s = 'A penny saved is a penny earned.'
print (s)
print(s.replace('n','l'))
print(s)
print(s.replace('penny','dollar'))
print(s.replace('penny','dollar',1))
輸出:
A penny saved is a penny earned.
A pelly saved is a pelly earled.
A penny saved is a penny earned.
A dollar saved is a dollar earned.
A dollar saved is a penny earned.