Error！

#我不知道怎么改才能消除语法错误，有没有大神帮我看一下？
class muffledcaculator:
muffled=False
def calc(self,expr):
try:
return eval(expr)
except ZeroDivisionError:
if muffled:
print 'division by zero is illege'
else :
raise
calculator=muffledcaculator()
calculator.calc('10/2')