code: func (v Vec3) Dist(v1 Vec3) float32 {
  	dx := v1[0] - v[0]
  	dy := v1[1] - v[1]
  	dz := v1[2] - v[2]
  	return math32.Sqrt(dx*dx + dy*dy + dz*dz)
  }
docs: // Dist returns the distance between v and v1. d = dist(v, v2)