message: Improve IPUOutfeedQueue documentation
  Summary: Improve the documentation of the `IPUOutfeedQueue` class.
  Reviewers: jamiep, #tensorflow, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved, hakons
  Subscribers: hakons, mariok, grahamh
  Maniphest Tasks: T25951
diff: @@ -45,6 +45,10 @@ class IPUOutfeedMode(Enum):
  class IPUOutfeedQueue:
  """Generates and adds outfeed enqueue/dequeue operations to the graph.
  + An outfeed is the counterpart to an infeed and manages the
  + transfer of data (like tensors, tuples or dictionaries of tensors)
  + from the IPU graph to the host.
  +
  The queue has two modes of operation - outfeed all or outfeed last.
  In outfeed all mode every element that is enqueued will be stored
  for a subsequent dequeue. All of the enqueued elements will be returned
  