code: func OpenBitmap(gpath string, args ...int) C.MMBitmapRef {
  	path := C.CString(gpath)
  	var mtype C.uint16_t = 1
  
  	if len(args) > 0 {
  		mtype = C.uint16_t(args[0])
  	}
  
  	bit := C.bitmap_open(path, mtype)
  	C.free(unsafe.Pointer(path))
  
  	return bit
  }
docs: // OpenBitmap open the bitmap return C.MMBitmapRef
  //
  // robotgo.OpenBitmap(path string, type int)