code: def networkproperties(self):
          
          print('Number of nodes: %d' % len(self.nodes))
          print('Number of elements: %d' % len(self.elements))
          print('Number of end nodes: %d' % len(self.endnodes))
          print('Number of distinct networks: %d' % len(self.numberofnetworks))
          print('Applied node variables: %s' % ', '.join(self.variables))
docs: Print out some properties of the network defined by the |Node| and
          |Element| objects currently handled by the |HydPy| object.