President Trump’s new get-tough attitude on immigration has already stopped one Mexican from coming to the United States.Trouble is, the Mexican who stayed home was President Enrique Pena Nieto.President Nieto wasn’t coming here illegally, and he wasn’t captured in Jeff Davis County, Texas, by one of Trump’s friends in the Border Patrol.But the Mexican leader and President Trump decided to scrap their planned summit next week after trading some testy tweets about whether or not Mexico was going to pay for a new wall along the U.S. southern border.Don’t worry.There won’t be another Mexican-American war.President Nieto will be back in good time and he and Donald will make their deal.But before the two leaders meet face-to-face - and before Trump starts spending his weekends in Texas pouring concrete footers on the border -- Trump should get his busy staff to dust off, update and improve the Bracero program.Most Americans - especially the politicians in Washington - have no idea what the Bracero program was.But from 1942 until 1964, when the federal government’s program was eliminated, it made illegal immigration from Mexico largely unnecessary by allowing the free flow of Mexican agricultural workers into and out of the United States.Over 22 years about 4.5 million Mexican nationals worked temporarily on the vegetable and fruit farms of California and the Southwest.The braceros were poor peasants. They were seasonal workers. They did hard agricultural work that not enough Americans were willing to do.They were greeted and processed by U.S. officials at collection stations at the border.They signed contracts with the farmers and companies that employed them, then worked long hours for low wages.It was far from perfect.