def set_file_logger(path, log_level=logging.DEBUG, format_string=None, logger_name='smc'):
    """
    Convenience function to quickly configure any level of logging
    to a file.

    :param int log_level: A log level as specified in the `logging` module
    :param str format_string: Optional format string as specified in the 
        `logging` module
    :param str path: Path to the log file.  The file will be created
        if it doesn't already exist.
    """
    if format_string is None: 
        format_string = LOG_FORMAT
    
    log = logging.getLogger(logger_name)
    log.setLevel(log_level)

    # create file handler and set level
    ch = logging.FileHandler(path)
    ch.setLevel(log_level)
    # create formatter
    formatter = logging.Formatter(format_string)
    # add formatter to ch
    ch.setFormatter(formatter)
    # add ch to logger
    log.addHandler(ch)