Python checkio "Long Non Repeat"解决方案

def non_repeat(line):    # your code here    result = ''    for i in range(len(line)):        value = ''        for j in range(i,len(line)):            char = line[j]            if char not in value:                value += char                if len(value) > len(result):result = value            else:                break    return resultdef non_repeat(s):    for l in range(len(s), 0, -1):        for i in range(0, len(s) - l + 1):            sub = s[i:i + l]            if all(sub.count(c) == 1 for c in sub):                return sub    return ''