code: def generate_code(self) -> Callable:
      def code(x, dst):
          dst[:] = x * 2
          return dst
  
      return code
  
imports: from dataclasses import replace
  import torch
  from ffcv.pipeline.allocation_query import AllocationQuery
  from ffcv.pipeline.compiler import Compiler
  import numpy
  from typing import Callable
  from assertpy import assert_that
  from torch.utils.data import Dataset
  import logging
  import os
  from assertpy import assert_that
  from tempfile import NamedTemporaryFile
  from ffcv.pipeline.operation import Operation
  from ffcv.transforms.ops import ToTensor
  from multiprocessing import cpu_count
  from ffcv.writer import DatasetWriter
  from ffcv.reader import Reader
  from ffcv.loader import Loader
  from ffcv.fields import IntField, FloatField, BytesField
  from ffcv.fields.basics import FloatDecoder
  from ffcv.pipeline.state import State
  from test_writer import DummyDataset
label_desc: Use image node_id 1 for calling the Doubler obj's underlying member method code with example usage: obj.generate_code() and returns: code, dst