docs: def _addProteins(self, proteinIds, containerNames):
          """Add one or multiple proteinIds to the respective container.
  
          :param proteinIds: a proteinId or a list of proteinIds, a proteinId
              must be a string.
          :param containerNames: list, entries must be one or multiple of
              'leading', 'subset', 'subsumableProteins' or 'proteins'
          :param addToProteins: bool, if True the proteinIds are added to the
          """
          proteinIds = AUX.toList(proteinIds)
          for containerName in containerNames:
              proteinContainer = getattr(self, containerName)
              proteinContainer.update(proteinIds)