code: def test_validate_multiprocessing_workers_None():
      """Test that validation does not fail when max_workers is None"""
      qs = QuantumScript(
          [qml.Rot(0.1, 0.2, 0.3, wires=0), qml.CNOT([0, 1])],
          [qml.expval(qml.PauliZ(1))],
      )
      device = qml.devices.DefaultQubit()
      validate_multiprocessing_workers(qs, None, device)
  
imports: import pytest
  import pennylane
  from pennylane.operation import Operation
  from pennylane.tape import QuantumScript
  from pennylane import DeviceError
  from pennylane.devices.preprocess import no_sampling, validate_device_wires, validate_multiprocessing_workers, validate_adjoint_trainable_params, _operator_decomposition_gen, decompose, validate_observables, validate_measurements
label_desc: Use image node_id 4 for calling a global function with example usage: test_validate_multiprocessing_workers_None() without return types