code: def add_graph(self, G):
      # first pass through G collecting edge ids
      for u, v, dd in G.edges(data=True):
          eid = dd.get("id")
          if eid is not None:
              self.all_edge_ids.add(str(eid))
      # set graph attributes
      if G.graph.get("mode") == "dynamic":
          mode = "dynamic"
      else:
          mode = "static"
      # Add a graph element to the XML
      if G.is_directed():
          default = "directed"
      else:
          default = "undirected"
      name = G.graph.get("name", "")
      graph_element = Element(
          "graph", defaultedgetype=default, mode=mode, name=name
      )
      self.graph_element = graph_element
      self.add_nodes(G, graph_element)
      self.add_edges(G, graph_element)
      self.xml.append(graph_element)
  
imports: import itertools
  import time
  from xml.etree.ElementTree import Element, ElementTree, SubElement, register_namespace, tostring
  import networkx
  from networkx.utils import open_file
label_desc: Use image node_id 3 for calling the GEXFWriter obj's underlying member method code with example usage: obj.add_graph(G) without return types