code: def test_CartanMatrix():
      c = CartanMatrix("A3")
      m = Matrix(3, 3, [2, -1, 0, -1, 2, -1, 0, -1, 2])
      assert c == m
      a = CartanMatrix(["G", 2])
      mt = Matrix(2, 2, [2, -1, -3, 2])
      assert a == mt
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_CartanMatrix() without return types