*return_when* indicates when this function should return. It must

be one of the following constants:

..tabularcolumns::|l|L|

| Constant| Description|

|:const:`FIRST_COMPLETED`| The function will return when any|

|| future finishes or is cancelled.|

|:const:`FIRST_EXCEPTION`| The function will return when any|

|| future finishes by raising an|

|| exception. If no future raises an|

|| exception then it is equivalent to|

||:const:`ALL_COMPLETED`.|

|:const:`ALL_COMPLETED`| The function will return when all|

|| futures finish or are cancelled.|

..list-table::

:header-rows: 1

* - Constant

- Description

* - .. data:: FIRST_COMPLETED

- The function will return when any future finishes or is cancelled.

* - .. data:: FIRST_EXCEPTION

- The function will return when any future finishes by raising an

exception. If no future raises an exception

then it is equivalent to:const:`ALL_COMPLETED`.

* - .. data:: ALL_COMPLETED

- The function will return when all futures finish or are cancelled.

Unlike:func:`~asyncio.wait_for`, ``wait()`` does not cancel the

futures when a timeout occurs.

Doc/library/asyncio-extending.rst

Doc/library/asyncio-policy.rst

Doc/library/asyncio-subprocess.rst

Doc/library/asyncio-task.rst

Doc/library/bdb.rst

Doc/library/collections.rst

Doc/library/concurrent.futures.rst