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The 12,000 volunteers who donned superhero capes and morphed San Francisco into Gotham City Friday can’t make sure a California boy will stay clear of leukemia for the rest of his life.

But, in handing the 5-year-old the key to the city, they can sure give him every boy’s dream come true for a few hours and a memory for a lifetime.

Right at 10 a.m. on Friday, Miles – a shy kindergartner with bright blue eyes and is in remission from his cancer – became “Batkid,” complete with mask, cape and puffy fake muscles. He exited the Batmobile, from the front of the two-person sportscar – of course – safety first – after unstrapping himself from his carseat.

“He’s just the cutest,” said Jackie Johnston, one of the thousands of fans who had come out to watch.

But Miles just isn’t cute. He’s a hero.