code: func WritePin(pin Pin, state State) {
  	p := uint8(pin)
  
  	// Set register, 7 / 8 depending on bank
  	// Clear register, 10 / 11 depending on bank
  	setReg := p/32 + 7
  	clearReg := p/32 + 10
  
  	memlock.Lock()
  
  	if state == Low {
  		gpioMem[clearReg] = 1 << (p & 31)
  	} else {
  		gpioMem[setReg] = 1 << (p & 31)
  	}
  	memlock.Unlock() // not deferring saves ~600ns
  }
docs: // WritePin sets a given pin High or Low
  // by setting the clear or set registers respectively