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...

Start with typeshed's engineio/async_drivers/eventlet.pyi and compare it with eventlet.py in the linked python-engineio source. Read the guarded import in engineio/base_server.py to understand when this driver is available. Done means choosing and documenting a supported stub approach for the missing eventlet dependency.