code: func (document *Document) GetSize() (int, int) {
  	width := C.long(0)
  	heigth := C.long(0)
  	C.get_document_size(document.handle, &width, &heigth)
  	return int(width), int(heigth)
  }
docs: // GetSize returns width and height of document in twips (1 Twip = 1/1440th of an inch)
  // You can convert twips to pixels by this formula: (width or height) * (1.0 / 1440.0) * DPI