class_docstr: test the private functions used in post processing.
docstr: Test the _batch_postprocessing helper function.
docstr_tok: ["Test","the","_batch_postprocessing","helper","function","."]
code: def test_batch_postprocessing(self):
      """Test the _batch_postprocessing helper function."""
      results = (1.0, 2.0, 3.0, 4.0)
  
      def postprocessing1(results):
          return results[0] + results[1]
  
      def postprocessing2(results):
          return results[0] + 1
  
      out = _batch_postprocessing(
          results,
          (postprocessing1, postprocessing2),
          [slice(0, 2), slice(2, 4)],
      )
      assert out == (3.0, 4.0)
  
imports: from typing import Sequence, Callable
  import pytest
  import pennylane
  from pennylane.tape import QuantumScript
  from pennylane.transforms.core import transform, TransformProgram, TransformError, TransformContainer
  from pennylane.transforms.core.transform_program import _batch_postprocessing, _apply_postprocessing_stack, null_postprocessing
  from pennylane.typing import ResultBatch, Result
label_desc: Use image node_id 1 for calling the TestUtilityHelpers obj's underlying member method code with example usage: obj.test_batch_postprocessing() and returns: unknown, unknown