code: def write(self, fh):
      # Serialize graph G in GEXF to the open fh
      if self.prettyprint:
          self.indent(self.xml)
      document = ElementTree(self.xml)
      document.write(fh, encoding=self.encoding, xml_declaration=True)
  
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 13 for calling the GEXFWriter obj's underlying member method code with example usage: obj.write(fh) without return types