hack for json reprs

def repr2_json(obj_, **kwargs):
    """ hack for json reprs """
    import utool as ut
    kwargs['trailing_sep'] = False
    json_str = ut.repr2(obj_, **kwargs)
    json_str = str(json_str.replace('\'', '"'))
    json_str = json_str.replace('(', '[')
    json_str = json_str.replace(')', ']')
    json_str = json_str.replace('None', 'null')
    return json_str