Function handshake 

pub async fn handshake<E, T, B>(
    exec: E,
    io: T,
) -> Result<(SendRequest<B>, Connection<T, B, E>)>
where
    T: Read + Write + Unpin,
    B: Body + 'static,
    B::Data: Send,
    B::Error: Into<Box<dyn Error + Send + Sync>>,
    E: Http2ClientConnExec<B, T> + Unpin + Clone,

Returns a handshake future over some IO.

This is a shortcut for Builder::new(exec).handshake(io). See client::conn for more.