docs: def eval(self, text):
          """Respond to text entered by the user.
  
          :param text: the user's input
          """
          program = Program(text, echo=self.echo, transforms=self.transforms)
          tokens = program.gen_tokens()
          for sentence in program.gen_sentences(tokens, self.aliases):
              if self.echo:
                  self.terminal.debug(str(sentence))
              program.interpret(sentence, self.commands)