code: def __str__(self):
      from xml.etree.ElementTree import tostring
  
      if self.prettyprint:
          self.indent(self.xml)
      s = tostring(self.xml).decode(self.encoding)
      return s
  
imports: import warnings
  from collections import defaultdict
  import networkx
  from networkx.utils import open_file
label_desc: Use image node_id 2 for calling the GraphMLWriter obj's underlying member method code with example usage: obj.__str__() and returns: s