Function subscribe 

pub fn subscribe<T>(
    table: &mut ResourceTable,
    resource: Resource<T>,
) -> Result<Resource<DynPollable>, Error>
where
    T: Pollable,

Creates a wasi:io/poll.pollable resource which is subscribed to the provided resource.

If resource is an owned resource then it will be deleted when the returned resource is deleted. Otherwise the returned resource is considered a “child” of the given resource which means that the given resource cannot be deleted while the pollable is still alive.