Question - how to write a stub file with missing imports?

I'm working on adding engineio to typeshed, and in its source code there is a file which imports from eventlet without a guard - https://github.com/miguelgrinberg/python-engineio/blob/main/src/engineio/async_drivers/eventlet.py#L1-L3.
the guard is in another part of the code - https://github.com/miguelgrinberg/python-engineio/blob/main/src/engineio/base_server.py#L82-L92

eventlet isn't even an optional dependency of engineio, but if it's installed and configured properly then the user's code can use engineio's eventlet driver

how should I approach this in the stub file of engineio/async_drivers/eventlet.pyi? I can't import from eventlet since it's not a dependency, but I also can't define the class WebSocketWSGI which inherits from the import eventlet.websocket.WebSocketWSGI

one possibility I've though of is to write a protocol which behaves like eventlet.websocket.WebSocketWSGI but that doesn't seem like the best approach...

typeshed's engineio/async_drivers/eventlet.pyi から始め、リンク先の python-engineio ソースにある eventlet.py と比較します。engineio/base_server.py のガードされた import を読み、このドライバーがいつ利用可能になるのかを理解します。欠落している eventlet 依存関係に対して、サポートされる stub のアプローチを選択して文書化できれば完了です。