if you're running a task on embassy-executor, it goes roughly like this:

- executor creates the waker
- executor calls Future::poll() on the task with the waker
- task polling gets to the leaf future (let's imagine it's an uart rx)
- leaf future checks hardware, sees no data has rx'd yet
- leaf future stores waker in a global, returns Pending
- data arrives, interrupt fires and calls .wake() on the waker
- the waker's vtable points to embassy-executor's implementation of wake(), which re-enqueues the task to be polled again