def mul(a,*args):

if args == ():

s=a

else:

s=a

for i in args:

s=s*i

return s

print('mul(5) =', mul(5))

print('mul(5, 6) =', mul(5, 6))

print('mul(5, 6, 7) =', mul(5, 6, 7))

print('mul(5, 6, 7, 9) =', mul(5, 6, 7, 9))

if mul(5) != 5:

print('测试失败!')

elif mul(5, 6) != 30:

print('测试失败!')

elif mul(5, 6, 7) != 210:

print('测试失败!')

elif mul(5, 6, 7, 9) != 1890:

print('测试失败!')

else:

try:

mul()

print('测试失败!')

except TypeError:

print('测试成功!')