#* coding: utf-8 *

def trim(s): if len(s) == 0: return s elif s[0] ==' ': return trim(s[1:]) elif s[-1] ==' ': return trim(s[:-1]) else: return s print(trim('hello ')) print(trim(' hello')) print(trim(' hello ')) print(trim(' hello world ')) print(trim('')) print(trim(' '))

if trim('hello ') != 'hello': print('测试失败!') elif trim(' hello') != 'hello': print('测试失败!') elif trim(' hello ') != 'hello': print('测试失败!') elif trim(' hello world ') != 'hello world': print('测试失败!') elif trim('') != '': print('测试失败!') elif trim(' ') != '': print('测试失败!') else: print('测试成功!')