docs: def generate_header(headerfields, oldheader, group_by_field):
      """Returns a header as a list, ready to write to TSV file"""
      fieldtypes = ['peptidefdr', 'peptidepep', 'nopsms', 'proteindata',
                    'precursorquant', 'isoquant']
      return generate_general_header(headerfields, fieldtypes,
                                     peptabledata.HEADER_PEPTIDE, oldheader,
                                     group_by_field)