code: def add_nodes(self, nodes, attr_dict=None, **attr):
          
          attr_dict = self._combine_attribute_arguments(attr_dict, attr)
  
          for node in nodes:
              # Note: This won't behave properly if the node is actually a tuple
              if type(node) is tuple:
                  # See ("B", {label="negative"}) in the documentation example
                  new_node, node_attr_dict = node
                  # Create a new dictionary and load it with node_attr_dict and
                  # attr_dict, with the former (node_attr_dict) taking precedence
                  new_dict = attr_dict.copy()
                  new_dict.update(node_attr_dict)
                  self.add_node(new_node, new_dict)
              else:
                  # See "A" in the documentation example
                  self.add_node(node, attr_dict.copy())
docs: Adds multiple nodes to the graph, along with any related attributes
              of the nodes.
  
          :param nodes: iterable container to either references of the nodes
                      OR tuples of (node reference, attribute dictionary);
                      if an attribute dictionary is provided in the tuple,
                      its values will override both attr_dict's and attr's
                      values.
          :param attr_dict: dictionary of attributes shared by all the nodes.
          :param attr: keyword arguments of attributes of the node;
                      attr's values will override attr_dict's values
                      if both are provided.
  
          See also:
          add_node
  
          Examples:
          ::
  
              >>> H = DirectedHypergraph()
              >>> attributes = {label: "positive"}
              >>> node_list = ["A",
                               ("B", {label="negative"}),
                               ("C", {root=True})]
              >>> H.add_nodes(node_list, attributes)