python 代码题01 利用切片，去除字符串首尾空格

def trim(s):
	if s[:1] !=' ' and s[-1:] !=' ':
		return s
	elif s[:1] ==' ':
		return trim(s[1:])
	else:
		return trim(s[:-1])
	
	
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!')