Bernie Sanders had to know that Stephen Colbert was going to ask him about Hillary Clinton’s new book. And the Vermont senator seemed very prepared to answer those questions when he appeared on The Late Show on Thursday night.

In her new campaign memoir, What Happened, Clinton writes that Sanders’ “attacks” on her progressive credentials “caused lasting damage, making it harder to unify progressives in the general election and paving the way for Trump’s ‘Crooked Hillary’ campaign.” She adds, “President Obama urged me to grit my teeth and lay off Bernie as much as I could. I felt like I was in a straitjacket.”

“Look, Secretary Clinton ran against the most unpopular candidate in the history of this country and she lost and was upset about that and I understand that,” Sanders told Colbert. “But our job now is really not to go backwards. It is to go forward. It is to create the kind of nation we know we can become. We have enormous problems facing us and I think it's a little bit silly to keep talking about 2016.”

Colbert, who will have Clinton on his show next week for her first late-night appearance since the election, asked Sanders how he would respond to her when she is sitting in that chair. “What do you think I should ask her?” the host inquired.

“I think the response is we have got to think going forward,” Sanders said, carefully, “and I would like her to join us in a fight for 15 [dollar minimum wage], in a Medicare-for-all single payer system, in taking on the fossil fuel industry so that we transform our energy system away from fossil fuel and move to energy efficient and sustainable energy.”

“So in other words, we need her help to go forward,” he continued. “Let’s not keep arguing about 2016. Let’s get together and take on Trump’s desire to divide us up. Let’s go forward with a progressive agenda.”

“Ask her if she’ll do that,” Sanders told Colbert.

Earlier in the evening, on MSNBC’s All In with Chris Hayes, Sanders responded to a section of Clinton’s book that references, of all things, the film There’s Something About Mary.

“A deranged hitchhiker says he’s come up with a brilliant plan. Instead of the famous ‘eight-minute abs’ exercise routine, he’s going to market ‘seven-minute abs.’ It’s the same, just quicker,” Clinton writes of the movie. “Then the driver, played by Ben Stiller, says, ‘Well, why not six-minute abs?’ That’s what it was like in policy debates with Bernie. We would propose a bold infrastructure investment plan or an ambitious new apprenticeship program for young people, and then Bernie would announce basically the same thing, but bigger.”

“Does anybody really believe that?” Sanders asked of the notion that he “stole” Clinton’s best ideas. “The truth is, and the real story is, that the ideas we brought forth in that campaign, which were so crazy and so radical, have increasingly become mainstream.”