code: func NewPointSetPreallocate(length, capacity int) *PointSet {
  	if length > capacity {
  		capacity = length
  	}
  
  	ps := make([]Point, length, capacity)
  	p := PointSet(ps)
  	return &p
  }
docs: // NewPointSetPreallocate simply creates a new point set with points array of the given size.