code: def _check_available_data(archive, arc_type, day):
      
      available_stations = []
      if arc_type.lower() == 'day_vols':
          wavefiles = glob.glob(os.path.join(archive, day.strftime('Y%Y'),
                                             day.strftime('R%j.01'), '*'))
          for wavefile in wavefiles:
              header = read(wavefile, headonly=True)
              available_stations.append((header[0].stats.station,
                                         header[0].stats.channel))
      elif arc_type.lower() == 'seishub':
          client = SeishubClient(archive)
          st = client.get_previews(starttime=UTCDateTime(day),
                                   endtime=UTCDateTime(day) + 86400)
          for tr in st:
              available_stations.append((tr.stats.station, tr.stats.channel))
      elif arc_type.lower() == 'fdsn':
          client = FDSNClient(archive)
          inventory = client.get_stations(starttime=UTCDateTime(day),
                                          endtime=UTCDateTime(day) + 86400,
                                          level='channel')
          for network in inventory:
              for station in network:
                  for channel in station:
                      available_stations.append((station.code,
                                                 channel.code))
      return available_stations
docs: Function to check what stations are available in the archive for a given \
      day.
  
      :type archive: str
      :param archive: The archive source
      :type arc_type: str
      :param arc_type: The type of archive, can be:
      :type day: datetime.date
      :param day: Date to retrieve data for
  
      :returns: list of tuples of (station, channel) as available.
  
      .. note:: Currently the seishub options are untested.