code: def close(self):
      self._closed = True
      # drain the q so the writer doesn't deadlock
      while not self._saw_eos:
          c = self._q.sync_q.get()
          if c is None:
              self._saw_eos = True
  
imports: from typing import BinaryIO, List, Optional, Tuple, Type
  from types import TracebackType
  import abc
  import io
  import os
  import sys
  from concurrent.futures import ThreadPoolExecutor
  import janus
  from hailtop.utils import blocking_to_async
  from .exceptions import UnexpectedEOFError
label_desc: Use image node_id 4 for calling the BlockingQueueReadableStream obj's underlying member method code with example usage: obj.close() without return types