code: def test_append_dimension():
      a = jnp.zeros((2, 3))
      b = util.append_dimension(a)
      assert b.shape == (2, 3, 1)
  
imports: from jax import numpy
  from jaxdf import util
  from jaxdf.operators.differential import gradient
label_desc: Use image node_id 1 for calling a global function with example usage: test_append_dimension() without return types