code: def add_node_ids_as_labels(discoursegraph):
      
      for node_id, properties in discoursegraph.nodes_iter(data=True):
          if 'label' not in properties and isinstance(node_id, (str, unicode)):
              discoursegraph.node[node_id]['label'] = ensure_utf8(node_id)
docs: Adds the ID of each node of a discourse graph as a label (an attribute
      named ``label`` with the value of the node ID) to itself. This will
      ignore nodes whose ID isn't a string or which already have a label
      attribute.
  
      Parameters
      ----------
      discoursegraph : DiscourseDocumentGraph