docs: def eff_default_transformer(fills=EFF_DEFAULT_FILLS):
      """
      Return a simple transformer function for parsing EFF annotations. N.B.,
      ignores all but the first effect.
  
      """
      def _transformer(vals):
          if len(vals) == 0:
              return fills
          else:
              # ignore all but first effect
              match_eff_main = _prog_eff_main.match(vals[0])
              if match_eff_main is None:
                  logging.warning(
                      'match_eff_main is None: vals={}'.format(str(vals[0]))
                  )
                  return fills
              eff = [match_eff_main.group(1)] \
                  + match_eff_main.group(2).split(b'|')
              result = tuple(
                  fill if v == b''
                  else int(v) if i == 5 or i == 10
                  else (1 if v == b'CODING' else 0) if i == 8
                  else v
                  for i, (v, fill) in enumerate(list(zip(eff, fills))[:11])
              )
              return result
      return _transformer