Function spawn_coroutine_with_buffer 

pub fn spawn_coroutine_with_buffer<T, F, Fut>(
    buffer: usize,
    f: F,
) -> CommunicationTask<T>
where
    F: FnMut(T) -> Fut + Send + 'static,
    Fut: Future<Output = ()> + Send + 'static,
    T: Send + 'static,

Spawns a new asynchronous task that accepts messages to the task with a set buffer. This function returns a handle that allows sending a message, or if there is no reference to the handle at all (in other words, all handles are dropped), the task would be aborted.