code: def run_pipeline(self, b_ix, batch_indices, batch_slot, cuda_event):
      self.memory_context.start_batch(b_ix)
      args = []
      if IS_CUDA:
          stream = self.cuda_streams[batch_slot]
          ctx = ch.cuda.stream(stream)
      else:
          ctx = nullcontext()
      first_stage = False
  
      code, outputs = self.loader.code
      with ctx:
          if IS_CUDA:
              if cuda_event:
                  cuda_event.wait()
  
          args = {
              "batch_indices": batch_indices,
              "storage_state": self.storage_state,
              "metadata": self.metadata,
              **{
                  f"memory_{k}": select_buffer(
                      v, batch_slot, len(batch_indices)
                  )
                  for (k, v) in self.memory_allocations[
                      "operation"
                  ].items()
              },
              **{
                  f"shared_memory_{k}": select_buffer(
                      v, batch_slot, len(batch_indices)
                  )
                  for (k, v) in self.memory_allocations[
                      "shared"
                  ].items()
              },
          }
  
          for stage_code, define_outputs in code:
              results = stage_code(**args)
              for node_id, result in zip(define_outputs, results):
                  args[f"result_{node_id}"] = result
              pass
  
          result = tuple(args[f"result_{x}"] for x in outputs)
          return result
  
file_path: ffcv/ffcv/loader/epoch_iterator.py
imports: from collections import defaultdict
  from threading import Thread, Event
  from queue import Queue, Full
  from contextlib import nullcontext
  from typing import Sequence, TYPE_CHECKING
  import torch
  from ..traversal_order.quasi_random import QuasiRandom
  from ..utils import chunks
  from ..pipeline.compiler import Compiler
label_desc: Use image node_id 3 for calling the EpochIterator obj's underlying member method code with example usage: obj.run_pipeline(b_ix, batch_indices, batch_slot, cuda_event) and returns: result