code: def is_complete(self):
          
          allocated = all(
              [node.route_allocation() is not None for node in list(self._nodes.values()) if node.name() != self._problem.depot().name()]
          )
  
          valid_routes = len(self._routes) == 1 #workaround: try to use only one route (otherwise process will stop if no of vehicles is reached)
  
          return allocated and valid_routes
docs: Returns True if this is a complete solution, i.e, all nodes are allocated
  
          Todo
          ----
          TO BE REVIEWED
          
          Returns
          -------
          bool
              True if this is a complete solution.