class_docstr: Executes a blocking function asynchronously on a queue of items.
code: def close(self):
      self._should_stop.set()
      # Join all background threads.
      self._thread.join()
      # Raise errors produced by background threads.
      self._raise_on_error()
  
file_path: acme/acme/utils/async_utils.py
imports: import queue
  import threading
  from typing import Callable, TypeVar, Generic
  from absl import logging
label_desc: Use image node_id 3 for calling the AsyncExecutor obj's underlying member method code with example usage: obj.close() without return types