code: def test_qimage_writethrough():
      w, h = 256, 256
      backstore = np.ones((h, w), dtype=np.uint8)
      ptr0 = backstore.ctypes.data
      fmt = pg.Qt.QtGui.QImage.Format.Format_Grayscale8
      qimg = pg.functions.ndarray_to_qimage(backstore, fmt)
  
      def get_pointer(obj):
          if hasattr(obj, "setsize"):
              return int(obj)
          else:
              return np.frombuffer(obj, dtype=np.uint8).ctypes.data
  
      # test that QImage is using the provided buffer (i.e. zero-copy)
      ptr1 = get_pointer(qimg.constBits())
      assert ptr0 == ptr1
  
      # test that QImage is not const (i.e. no COW)
      # if QImage is const, then bits() returns a copy
      ptr2 = get_pointer(qimg.bits())
      assert ptr1 == ptr2
  
      # test that data gets written through to provided buffer
      qimg.fill(0)
      assert np.all(backstore == 0)
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_qimage_writethrough() and returns: int, np