code: func (f *Fpdf) Line(x1, y1, x2, y2 float64) {
  	f.outf("%.2f %.2f m %.2f %.2f l S", x1*f.k, (f.h-y1)*f.k, x2*f.k, (f.h-y2)*f.k)
  }
docs: // Line draws a line between points (x1, y1) and (x2, y2) using the current
  // draw color, line width and cap style.