#coding=utf-8#!/usr/bin/pythonstr1 = None;str2 = '';str3 = ' ';if str1 == None : print("str1 is none.");else : print("str1 is not none.");if str2 == None : print("str2 is none.");else : print("str2 is not none.");if str2 == None or len(str2) == 0 : print("str2 is none.");else : print("str2 is not none.");if str3 == None or len(str3.strip()) == 0 : print("str3 is none.");else : print("str3 is not none.");