code: def __call__(self, stream):
      self.xml = ElementTree(file=stream)
      g = self.xml.find(f"{{{self.NS_GEXF}}}graph")
      if g is not None:
          return self.make_graph(g)
      # try all the versions
      for version in self.versions:
          self.set_version(version)
          g = self.xml.find(f"{{{self.NS_GEXF}}}graph")
          if g is not None:
              return self.make_graph(g)
      raise nx.NetworkXError("No <graph> element in GEXF file.")
  
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 2 for calling the GEXFReader obj's underlying member method code with example usage: obj.__call__(stream) and returns: self, self