code: def test_gt():
      d = gt(1)
      assert isinstance(d, GT)
      assert d.val == 1
  
      o = d.to_json()
      assert isinstance(o, dict)
      assert o["type"] == "GT"
      assert o["val"] == 1
  
      d2 = GT.from_json(o)
      assert isinstance(d2, GT)
      assert d2.val == 1
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_gt() without return types