code: func (f *Fpdf) Polygon(points []PointType, styleStr string) {
  	if len(points) > 2 {
  		for j, pt := range points {
  			if j == 0 {
  				f.point(pt.X, pt.Y)
  			} else {
  				f.outf("%.5f %.5f l ", pt.X*f.k, (f.h-pt.Y)*f.k)
  			}
  		}
  		f.outf("%.5f %.5f l ", points[0].X*f.k, (f.h-points[0].Y)*f.k)
  		f.DrawPath(styleStr)
  	}
  }
docs: // Polygon draws a closed figure defined by a series of vertices specified by
  // points. The x and y fields of the points use the units established in New().
  // The last point in the slice will be implicitly joined to the first to close
  // the polygon.
  //
  // styleStr can be "F" for filled, "D" for outlined only, or "DF" or "FD" for
  // outlined and filled. An empty string will be replaced with "D". Drawing uses
  // the current draw color and line width centered on the ellipse's perimeter.
  // Filling uses the current fill color.