code: def test_Gradient():
      assert Gradient(s1) == Gradient(R.x * R.y * R.z)
      assert Gradient(s2) == Gradient(R.x + 3 * R.y**2)
      assert (
          Gradient(s1).doit()
          == R.y * R.z * R.i + R.x * R.z * R.j + R.x * R.y * R.k
      )
      assert Gradient(s2).doit() == R.i + 6 * R.y * R.j
  
imports: from sympy.vector import CoordSys3D, Gradient, Divergence, Curl, VectorZero, Laplacian
  from sympy.printing.repr import srepr
label_desc: Use image node_id 1 for calling a global function with example usage: test_Gradient() without return types