Python报错——object of type ‘NoneType‘ has no len()

直接用len()会报错，object of type ‘NoneType’ has no len()

if 6 == len(v):
	v = '19' + v

输入的v正常情况下是字符串类型，出现了异常类型导致报错
加一个类型判断和转换，即可解决这个报错

if type(v) != 'str':
	v = str(v)
if 6 == len(v):
   	v = '19' + v