code: func NewPool(seed int64, size uint64) *Pool {
  	groupsize := nextNearestPow2uint64(size)
  	pool := &Pool{
  		size:    groupsize,
  		sources: make([]NumberGenerator, groupsize),
  	}
  	// seed the pool
  	pool.seed(seed)
  	return pool
  }
docs: // NewPool takes in a size and creates a pool of random id generators with size equal to next closest power of 2.
  // eg: NewPool(10) returns a pool with 2^4 = 16 random sources.