It’s nostalgic, remembering the Polish-Jewish actor from Brooklyn — Eli Wallach — leading his army of Mexican criminals against Vladivostok native Yul Brynner and his six fellow American gunslingers.

Sometimes, when I listen to people worrying over the hordes of criminals pouring over the southern border, I hear the strains of Elmer Bernstein’s great “Magnificent Seven” theme song playing inside my head, and Eli Wallach is once again driving his band of desperados, hell bent for leather, through the desert.

It’s nostalgic, remembering the Polish-Jewish actor from Brooklyn — Eli Wallach — leading his army of Mexican criminals against Vladivostok native Yul Brynner and his six fellow American gunslingers.

In one of my favorite scenes, Wallach, playing bandit leader Calvera, looks around at the town square he plans to plunder.

“New wall,” he says.

“There are lots of new walls, all around,” replies Brynner, playing Chris, the gunslinger leading the defense of the farm town.

“They won’t keep me out!” scoffs Calvera.

“They were built to keep you in,” Chris replies in an impressively matter-of-fact tone, considering how much shooting is about to occur.

Experts say that the best use of Mexican border walls is for exactly that purpose: to keep the bad guys in the United States.

The walls we currently have, principally dividing U.S. towns from Mexican sister cities, are most effective when our own cops are chasing people around our own territory. The bandits can’t so easily escape south.

Soon after Donald Trump was elected, he sent the Army down to fix up some of the existing walls, which was fine. The least-appreciated improvement was putting concertina wire along the tops.

It’s obviously of scant practical use in that setting. The tall fence is sufficient. What it does is what concertina wire does best: say something about people on one side of the barrier or the other.

In this case, it speaks loudest about the people who put it up.

The wall-to-wall wall that Trump wants would speak very loudly, indeed. And once it gets out into open country, forget about it remaining non-scalable, or even intact, no matter how scary you make it look. You can’t have cops posted every few feet to make sure people aren’t busy defeating it.

That’s why factory operators turn vicious dogs loose all night on their side of walls and fences.

Maybe that’s part of Trump’s plan.

Just as the existing border walls are mostly effective in keeping in the bad guys who are plying their trade in the United States, so would the big wall, but in a slightly different way.

We know what will happen, because the immigration crackdowns of the last decade have already discouraged illegal aliens from leaving the United States.

They’re afraid of not being able to get back in.

So, now we’ve got several classes of Mexican people who are kind of stuck in the United States, and feel they cannot return to visit their families back home annually, or however often, the way they used to.

Do we want criminal illegals to set up housekeeping here in the United States? That’s what we’ve set in motion, long before Trump decided to make it worse.

Many people whose only crime is their immigration status, who originally came here to work seasonally, feel stuck, too. Among them are young men who work at underpaid jobs, but can abide the low pay because they keep their expenses down by cramming into apartments together. The plan was to live here temporarily, and send cash back home.

But now they’re stuck here, and still making short money. What to do, what to do?

Become criminals? In a way.

One of the things some are doing is taking advantage of a thriving underground business in false documentation.

That way, they can get better jobs, and stay, like, forever.

American citizens may be familiar with this trade, because illegal aliens aren’t the only ones who need false documents. High school kids get thirsty.

I assume that most American citizens who — for years — have had a low opinion of Mexicans are those who do not really know them. These Americans must not be among those who return from longish trips to Mexico, enthusing about the hospitality and kindness they found there.

The illegals came here steeped in that culture of kindness, and upon arrival, usually became even more forgiving of slights against their persons.

After all, if you’re in a country illegally, you don’t make a fuss about every little thing.

Many American business owners learned many decades ago that people like this make terrific employees. Nice people who are even nicer because of fear.

There was a time when you couldn’t walk down a block, anywhere in Chicago, and be sure there wasn’t an illegal Mexican worker laboring at something.

Years ago, it was so out-in-the-open. When I used to deliver restaurant supplies, I had to be aware of which kitchens I couldn’t arrive at early, because I’d disturb the busboys who were sleeping on the floor.

Even in this decade, I’ve seen processed food factories staffed almost entirely by illegals.

Why was it so often worth the risk? The fines employers paid if convicted of hiring outside the law were purposely kept low enough for it not to be a factor.

This is why corporations donate to political campaigns.

And it’s still legal to bring “guest workers” into the United States, where they can labor in fields and processing plants — often, for low wages and under dangerous working conditions.

This allows us to buy produce and other farm products much cheaper than Europeans do. Politicians think we insist on that. Maybe we do.

It also fits into our foreign trade system. We get manufactured goods from overseas built by underpaid labor, and we send back our own versions.

Trump insists it’s a national emergency to buy a $5.7 billion border wall to keep out generally nice, meek people who’ve been doing our grunt work for low pay and no benefits for decades.

At the same time, Miami needs about $14 billion to prevent pollution from infiltrating its drinking water supply from one side, and the Atlantic Ocean from the other. They’ve got about 20 years to get the job done, and they’ve got a long way to go.

But there’s no national emergency there.

Now, you might say Florida’s got it coming, because the residents, in general, have let corporations despoil their environment, and they refuse to pay normal taxes to fix their problems once they occur.

But they’re in deep trouble, no matter whose fault it is.

Hopefully, there will be enough Mexicans in the state to get the job done.