code: func nextNearestPow2uint64(v uint64) uint64 {
  	v--
  	v |= v >> 1
  	v |= v >> 2
  	v |= v >> 4
  	v |= v >> 8
  	v |= v >> 16
  	v |= v >> 32
  	v++
  	return v
  }
docs: // see bit twiddling hacks: https://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2