code: func (v *Layout) SetMarkup(text string, length int) {
  	cstr := C.CString(text)
  	defer C.free(unsafe.Pointer(cstr))
  	C.pango_layout_set_markup(v.native(), (*C.char)(cstr), (C.int)(length))
  }
docs: //void           pango_layout_set_markup     (PangoLayout    *layout,
  //					    const char     *markup,
  //					    int             length);