code: def label(self, nid, id_if_null=False):
          
          g = self.get_graph()
          if nid in g:
              n = g.node[nid]
              if 'label' in n:
                  return n['label']
              else:
                  if id_if_null:
                      return nid
                  else:
                      return None
          else:
              if id_if_null:
                  return nid
              else:
                  return None
docs: Fetches label for a node
  
          Arguments
          ---------
          nid : str
              Node identifier for entity to be queried
          id_if_null : bool
              If True and node has no label return id as label
  
          Return
          ------
          str