def METHOD_NAME(line):
    """Parse a line for an iotime message produced by `format`
    Args:
        line (str): the line to parse
    Returns None if no match, or dict with keys function,duration,readwrite,filename,timestamp
    """
    m = _iotime_regex.match(line)
    if m is not None:
        prefix, duration, readwrite, filename, timestamp = m.groups()
        duration = float(duration)
        logmatch = _log_regex.match(line)
        if prefix == '' or logmatch is None:
            function = 'unknown'
        else:
            function = logmatch.group(4)
        return dict(
            function=function, duration=duration, readwrite=readwrite,
            filename=filename, timestamp=timestamp)
    else:
        return None