Macro ready_some 

macro_rules! ready_some {
    ($e:expr) => { ... };
}

Unwrap the value from a Poll<Option<T>>, early-returning from the enclosing function on Ready(None) or Pending.

Must be invoked inside a function returning Poll<Option<_>>, such as a Stream::poll_next impl; the return arms otherwise produce a type mismatch at the enclosing function’s return.