<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _get_station_file(path_name, station, channel, debug=0):
 """ Helper function to find the correct file. :type path_name: str :param path_name: Path to files to check. :type station: str :type channel: str :returns: list of filenames, str """

    wavfiles = glob.glob(path_name + os.sep + '*')

    out_files = [_check_data(wavfile, station, channel, debug=debug)
                 for wavfile in wavfiles]
    out_files = list(set(out_files))
    return out_files