code: def parsecmap(self, fn):
          '''Returns a parser that transforms the produced value of parser with `fn`.'''
          return self.bind(lambda res: Parser(lambda _, index: Value.success(index, fn(res)))f parsecmap(self, fn):
          '''Returns a parser that transforms the produced value of parser with `fn`.'''
          return self.bind(lambda res: Parser(lambda _, index: Value.success(index, fn(res))))
docs: Returns a parser that transforms the produced value of parser with `fn`.