docstr: Test executing multiple steps of the RotosolveOptimizer on a QNode.
docstr_tok: ["Test","executing","multiple","steps","of","the","RotosolveOptimizer","on","a","QNode","."]
code: def test_multiple_steps(
      self,
      qnode,
      param,
      nums_frequency,
      spectra,
      substep_optimizer,
      substep_kwargs,
  ):
      """Test executing multiple steps of the RotosolveOptimizer on a QNode."""
      param = tuple(np.array(p, requires_grad=True) for p in param)
      # For the following 1D substep_optimizer, the bounds need to be expanded for these QNodes
      if substep_optimizer in ["shgo", custom_optimizer]:
          substep_kwargs["bounds"] = ((-2.0, 2.0),)
      opt = RotosolveOptimizer(substep_optimizer, substep_kwargs)
  
      repack_param = len(param) == 1
      initial_cost = qnode(*param)
  
      for _ in range(3):
          param = opt.step(
              qnode,
              *param,
              nums_frequency=nums_frequency,
              spectra=spectra,
          )
          # The following accounts for the unpacking functionality for length-1 param
          if repack_param:
              param = (param,)
  
      assert qnode(*param) < initial_cost
  
imports: import functools
  import pytest
  from scipy.optimize import shgo
  import pennylane
  from pennylane import numpy
  from pennylane.utils import _flatten, unflatten
  from pennylane.optimize import RotosolveOptimizer
label_desc: Use image node_id 2 for calling the TestWithQNodes obj's underlying member method code with example usage: obj.test_multiple_steps(qnode, param, nums_frequency, spectra, substep_optimizer, substep_kwargs) without return types