code: def __str__(self):
      if self.prettyprint:
          self.indent(self.xml)
      s = tostring(self.xml).decode(self.encoding)
      return s
  
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 GEXFWriter obj's underlying member method code with example usage: obj.__str__() and returns: s