class_docstr: This tracks all pending frees corresponding to inflight all-gathers. The
  queueing pattern is iterative enqueues with a single dequeue per iteration
  once the limit ``_max_num_inflight_all_gathers`` is reached.
docstr: Dequeues a single event if the limit is reached.
docstr_tok: ["Dequeues","a","single","event","if","the","limit","is","reached","."]
code: def dequeue_if_needed(self) -> Optional[torch.cuda.Event]:
      """Dequeues a single event if the limit is reached."""
      if len(self._queue) >= self._max_num_inflight_all_gathers:
          return self._dequeue()
      return None
  
file_path: pytorch/torch/distributed/fsdp/_limiter_utils.py
imports: import collections
  from typing import Deque, Optional
  import torch
label_desc: Use image node_id 3 for calling the _FreeEventQueue obj's underlying member method code with example usage: obj.dequeue_if_needed() and returns: None, self