logs parameters and result - takes no arguments

def log(fn=None, logger=logging.getLogger(), debug_level=logging.DEBUG):
    """
    logs parameters and result - takes no arguments
    """
    if fn is None:
        return partial(log, logger=logger, debug_level=debug_level)

    @wraps(fn)
    def func(*args, **kwargs):
        arg_string = ""
        for i in range(0, len(args)):
            var_name = fn.__code__.co_varnames[i]
            if var_name not in ['self', 'cls']:
                arg_string += var_name + ":" + str(args[i]) + ","
        arg_string = arg_string[0:len(arg_string) - 1]
        string = (RED + BOLD + '>> ' + END + 'Calling {0}({1})'.format(fn.__name__, arg_string))
        if len(kwargs):
            string = (
                RED + BOLD + '>> ' + END + 'Calling {0} with args {1} and kwargs {2}'.format(fn.__name__, arg_string,
                                                                                             kwargs))
        logger.log(debug_level, string)
        wrapped_fn = fn
        if not asyncio.iscoroutine(fn):
            wrapped_fn = asyncio.coroutine(fn)
        try:
            result = yield from wrapped_fn(*args, **kwargs)
            string = BLUE + BOLD + '<< ' + END + 'Return {0} with result :{1}'.format(fn.__name__, result)
            logger.log(debug_level, string)
            return result
        except Exception as e:
            string = (RED + BOLD + '>> ' + END + '{0} raised exception :{1}'.format(fn.__name__, str(e)))
            logger.log(debug_level, string)
            raise e

    return func