code: def del_node(self, node):
          
          for each in list(self.neighbors(node)):
              if (each != node):
                  self.del_edge((each, node))
          del(self.node_neighbors[node])
          del(self.node_attr[node])
docs: Remove a node from the graph.
          
          @type  node: node
          @param node: Node identifier.