Sean Parker crafted a little-known part of the tax code called Opportunity Zones. Now every one-percenter in Silicon Valley wants in. The men and women who serve as financial aides de camp to Silicon Valley’s billionaires are brimming with phone calls from curious clients. “Hey, I was talking to my buddy about this. It sounds too good to be true. Can you help me understand?” That’s how tax accountant Mike Bernier describes his conversations this fall around “Opportunity Zones” — the hot new thing in the land of the mega wealthy.