code: def classify_by_name(names):
      
      if len(names) > 3:  # Polymer
          if len(set(config.RNA).intersection(set(names))) != 0:
              ligtype = 'RNA'
          elif len(set(config.DNA).intersection(set(names))) != 0:
              ligtype = 'DNA'
          else:
              ligtype = "POLYMER"
      else:
          ligtype = 'SMALLMOLECULE'
  
      for name in names:
          if name in config.METAL_IONS:
              if len(names) == 1:
                  ligtype = 'ION'
              else:
                  if "ION" not in ligtype:
                      ligtype += '+ION'
      return ligtype
docs: Classify a (composite) ligand by the HETID(s)