code: def selection(self):
          
          return selectiontools.Selection(
              self.selection_name, self.nodes, self.elements)
docs: A complete |Selection| object of all "supplying" and "routing"
          elements and required nodes.
  
          >>> from hydpy import RiverBasinNumbers2Selection
          >>> rbns2s = RiverBasinNumbers2Selection(
          ...                            (111, 113, 1129, 11269, 1125, 11261,
          ...                             11262, 1123, 1124, 1122, 1121))
          >>> rbns2s.selection
          Selection("complete",
                    nodes=("node_1123", "node_1125", "node_11269", "node_1129",
                           "node_113", "node_outlet"),
                    elements=("land_111", "land_1121", "land_1122", "land_1123",
                              "land_1124", "land_1125", "land_11261",
                              "land_11262", "land_11269", "land_1129",
                              "land_113", "stream_1123", "stream_1125",
                              "stream_11269", "stream_1129", "stream_113"))
  
          Besides the possible modifications on the names of the different
          nodes and elements, the name of the selection can be set differently:
  
          >>> rbns2s.selection_name = 'sel'
          >>> from hydpy import pub
          >>> with pub.options.ellipsis(1):
          ...     print(repr(rbns2s.selection))
          Selection("sel",
                    nodes=("node_1123", ...,"node_outlet"),
                    elements=("land_111", ...,"stream_113"))