code: func (p *Point) Round(factor ...int) *Point {
  	f := 1.0e5
  	if len(factor) != 0 {
  		f = float64(factor[0])
  	}
  
  	for idx, val := range p {
  		x := val * f
  		p[idx] = math.Floor(x+0.5) / f
  	}
  
  	return p
  }
docs: // Round returns a point which coordinates are rounded
  // Factor defaults to 1.0e5