code: def _insert_optional_roles(cursor, model, ident):
      
      optional_roles = [
          # (<metadata-attr>, <db-role-id>,),
          ('translators', 4,),
          ('editors', 5,),
      ]
      for attr, role_id in optional_roles:
          roles = model.metadata.get(attr)
          if not roles:
              # Bail out, no roles for this type.
              continue
          usernames = [parse_user_uri(x['id']) for x in roles]
          cursor.execute("""\
  INSERT INTO moduleoptionalroles (module_ident, roleid, personids)
  VALUES (%s, %s, %s)""", (ident, role_id, usernames,))
docs: Inserts the optional roles if values for the optional roles
      exist.