code: def list_files(tag=None, sat_id=None, data_path=None, format_str=None):
      
  
      desc = None
      level = tag
      if level == 'level_1':
          code = 'L1'
          desc = None
      elif level == 'level_2':
          code = 'L2'
          desc = None
      else:
          raise ValueError('Unsupported level supplied: ' + level)
  
      if format_str is None:
          format_str = 'ICON_'+code+'_EUV_Daytime'
          if desc is not None:
              format_str += '_' + desc +'_'
          format_str += '_{year:4d}-{month:02d}-{day:02d}_v{version:02d}r{revision:03d}.NC'
  
      return pysat.Files.from_os(data_path=data_path,
                                  format_str=format_str)
docs: Produce a list of ICON EUV files.
  
      Notes
      -----
      Currently fixed to level-2