code: def identify_HPX_convention(header):
          
          # Hopefully the file contains the HPX_CONV keyword specifying
          # the convention used
          try:
              return header['HPX_CONV']
          except KeyError:
              pass
  
          indxschm = header.get('INDXSCHM', None)
  
          # Try based on the EXTNAME keyword
          extname = header.get('EXTNAME', None)
          if extname == 'HPXEXPOSURES':
              return 'FGST_BEXPCUBE'
          elif extname == 'SKYMAP2':
              if 'COORDTYPE' in header.keys():
                  return 'GALPROP'
              else:
                  return 'GALPROP2'
  
          # Check for the INDXSCHM keyword
          if indxschm == 'SPARSE':
              return 'FGST_SRCMAP_SPARSE'
  
          # Check the name of the first column
          colname = header['TTYPE1']
          if colname == 'PIX':
              colname = header['TTYPE2']
  
          if colname == 'KEY':
              return 'FGST_SRCMAP_SPARSE'
          elif colname == 'ENERGY1':
              return 'FGST_TEMPLATE'
          elif colname == 'COSBINS':
              return 'FGST_LTCUBE'
          elif colname == 'Bin0':
              return 'GALPROP'
          elif colname in ['CHANNEL1', 'Bin 0']:
              if extname == 'SKYMAP':
                  return 'FGST_CCUBE'
              else:
                  return 'FGST_SRCMAP'
          else:
              raise ValueError("Could not identify HEALPix convention")
docs: Identify the convention used to write this file