docs: def add_psms_to_proteindata(proteindata, p_acc, pool, psmdata):
      """Fill function for create_featuredata_map"""
      seq, psm_id = psmdata[2], psmdata[3]
      try:
          proteindata[p_acc]['pools'][pool]['psms'].add(psm_id)
      except KeyError:
          emptyinfo = {'psms': set(), 'peptides': set(), 'unipeps': 0}
          try:
              proteindata[p_acc]['pools'][pool] = emptyinfo
          except KeyError:
              proteindata[p_acc].update({'pools': {pool: emptyinfo}})
          proteindata[p_acc]['pools'][pool]['psms'].add(psm_id)
      proteindata[p_acc]['pools'][pool]['peptides'].add(seq)