code: def finish_off(self):
          
          self.keywords = {} # map from keyword strings to arc labels
          self.tokens = {}   # map from numeric token values to arc labels
          for ilabel, (type, value) in enumerate(self.labels):
              if type == token.NAME and value is not None:
                  self.keywords[value] = ilabel
              elif value is None:
                  self.tokens[type] = ilabel
docs: Create additional useful structures.  (Internal).