test.py

import re


def valid_username(string):
    """
    >>> valid_username('a')
    True
    >>> valid_username('brad')
    True
    >>> valid_username('0')
    True
    >>> valid_username('123')
    True
    >>> valid_username('brad1979')
    True
    >>> valid_username('-brad-1979-')
    True
    >>> valid_username('_brad_1979_')
    True
    >>> valid_username("brad's_username")
    True
    >>> valid_username('brad+andrea')
    True
    >>> valid_username('*b*r*a*d*')
    True
    >>> valid_username('*')
    True
    >>> valid_username('$$$brad$$$')
    True
    >>> valid_username('$')
    True
    >>> valid_username('b^r^a^d')
    True
    >>> valid_username('br&rea')
    True
    >>> valid_username('%%%%%%%%%%%%%%%%%%%%%%')
    True
    >>> valid_username('brad===awesome')
    True
    >>> valid_username('~~~brad~~~')
    True
    >>> valid_username('brad!!!!')
    True
    >>> valid_username('?b')
    True
    >>> valid_username('br{and}rea')
    True
    >>> valid_username('{')
    True
    >>> valid_username('}')
    True
    >>> valid_username('é')
    False
    >>> valid_username('ñ')
    False
    >>> valid_username('br(and)rea')
    False
    >>> valid_username('"brad"')
    False
    >>> valid_username('@')
    False
    >>> valid_username('00000000000000000000000000000000000000000')
    False
    >>> valid_username('###')
    False
    """
    return bool(
        re.search('^[a-z0-9_-\'+*$^&%=~!?{}]+$', string, re.I)
        and len(string) < 65
    )