code: func (f *Fpdf) TransformMirrorLine(angle, x, y float64) {
  	f.TransformScale(-100, 100, x, y)
  	f.TransformRotate(-2*(angle-90), x, y)
  }
docs: // TransformMirrorLine symmetrically mirrors the following text, drawings and
  // images on the line defined by angle and the point (x, y). angles is
  // specified in degrees and measured counter-clockwise from the 3 o'clock
  // position.
  //
  // The TransformBegin() example demonstrates this method.