code: def add_start_end(self, data, xml):
      # start and end times
      ttype = self.timeformat
      node_start = xml.get("start")
      if node_start is not None:
          data["start"] = self.python_type[ttype](node_start)
      node_end = xml.get("end")
      if node_end is not None:
          data["end"] = self.python_type[ttype](node_end)
      return data
  
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 5 for calling the GEXFReader obj's underlying member method code with example usage: obj.add_start_end(data, xml) and returns: data