code: func (c Circle) Norm() Circle {
  	return Circle{
  		Center: c.Center,
  		Radius: math.Abs(c.Radius),
  	}
  }
docs: // Norm returns the Circle in normalized form - this sets the radius to its absolute value.
  //
  // c := pixel.C(-10, pixel.ZV)
  // c.Norm() // returns pixel.Circle{pixel.Vec{0, 0}, 10}