code: func (ps *PointSet) Pop() *Point {
  	deref := *ps
  	if len(deref) == 0 {
  		return nil
  	}
  
  	x := deref[len(deref)-1]
  	*ps = deref[:len(deref)-1]
  
  	return &x
  }
docs: // Pop removes and returns the last point in the point set