code: func (f *Fpdf) SetPageBox(t string, x, y, wd, ht float64) {
  	f.SetPageBoxRec(t, PageBox{SizeType{Wd: wd, Ht: ht}, PointType{X: x, Y: y}})
  }
docs: // SetPageBox sets the page box for the current page, and any following pages.
  // Allowable types are trim, trimbox, crop, cropbox, bleed, bleedbox, art and
  // artbox box types are case insensitive.