code: def get_token(self, token_node_id, token_attrib='token'):
          
          return self.node[token_node_id][self.ns+':'+token_attrib]
docs: given a token node ID, returns the token unicode string.
  
          Parameters
          ----------
          token_node_id : str
              the ID of the token node
          token_attrib : str
              name of the node attribute that contains the token string as its
              value (default: token).
  
          Returns
          -------
          token : unicode
              the token string