code: def test_plain_indexing():
      data = [
          np.float32([[0, 1, 2], [3, 4, 5]]),
          np.float32([[0, 1], [2, 3], [4, 5]]),
      ]
      src = fn.external_source(lambda: data, layout="AB")
      pipe = index_pipe(src, lambda x: x[1, 1])
      pipe.build()
      inp, cpu, gpu = pipe.run()
      for i in range(len(inp)):
          x = inp.at(i)
          assert np.array_equal(x[1, 1], cpu.at(i))
          assert np.array_equal(x[1, 1], gpu.as_cpu().at(i))
  
imports: from nvidia import dali
  from nvidia.dali import fn
  import numpy
  from nvidia.dali.pipeline import Pipeline
  from nose_utils import assert_raises
label_desc: Use image node_id 2 for calling a global function with example usage: test_plain_indexing() without return types