code: def valid_instance(request):
      yield request.param
  
file_path: pennylane/tests/ops/functions/conftest.py
imports: from inspect import getmembers, isclass
  import pytest
  import numpy
  import pennylane
  from pennylane.operation import Operator, Operation, Observable, Tensor, Channel
  from pennylane.operation import DiagGatesUndefinedError, MatrixUndefinedError
  from pennylane.ops.op_math.adjoint import Adjoint, AdjointObs, AdjointOperation, AdjointOpObs
  from pennylane.ops.op_math.pow import PowObs, PowOperation, PowOpObs
label_desc: Use image node_id 3 for calling a global function with example usage: valid_instance(request) without return types