code: def setUp(self) -> None:
      self.native_functions: List[NativeFunction] = []
      self.backend_indices: Dict[
          DispatchKey, Dict[OperatorName, BackendMetadata]
      ] = defaultdict(dict)
      yaml_entry = """
  - func: op(Tensor self) -> Tensor
    dispatch:
      CompositeExplicitAutograd: op
    autogen: op.out
          """
      es = yaml.load(yaml_entry, Loader=LineLoader)
      self.one_return_func, m = NativeFunction.from_yaml(
          es[0], loc=Location(__file__, 1), valid_tags=set()
      )
  
      BackendIndex.grow_index(self.backend_indices, m)
  
      (
          self.two_returns_func,
          two_returns_backend_index,
      ) = NativeFunction.from_yaml(
          {
              "func": "op_2() -> (Tensor, Tensor)",
              "dispatch": {"CPU": "kernel_1"},
              "autogen": "op_2.out",
          },
          loc=torchgen.model.Location(__file__, 1),
          valid_tags=set(),
      )
      BackendIndex.grow_index(
          self.backend_indices, two_returns_backend_index
      )
  
imports: import dataclasses
  import typing
  import unittest
  from collections import defaultdict
  from typing import Dict, List
  import torchgen.model
  import yaml
  from tools.autograd import gen_autograd_functions, load_derivatives
  from torchgen import dest
  from torchgen.api.types import CppSignatureGroup, DispatcherSignature
  from torchgen.context import native_function_manager
  from torchgen.gen import get_native_function_declarations, get_native_function_schema_registrations, LineLoader, static_dispatch
  from torchgen.model import BackendIndex, BackendMetadata, DispatchKey, Location, NativeFunction, OperatorName
  from torchgen.native_function_generation import add_generated_native_functions
  from torchgen.selective_build.selector import SelectiveBuilder
label_desc: Use image node_id 1 for calling the TestNativeFunctionGeneratrion obj's underlying member method code with example usage: obj.setUp() without return types