/// Construct a new handler composed of a HandlerFunc with state, and an optional next handler
/// in the chain.
Construct a new handler composed of a HandlerFunc with state, and an optional next handler
in the chain.
Construct a new handler composed of a HandlerFunc with state and an optional next handler in the chain .
pub fn new(handler: HandlerFunc<S, T>, next: Option<Handler<S, T>>) -> Self {
        Self {
            handler,
            next: Box::new(next),
        }
    }
pub fn new ( handler : HandlerFunc < S , T > , next : Option < Handler < S , T > > ) -> Self { Self { handler , next : Box :: new ( next ) , } }
Construct a new handler composed of a HandlerFunc with state, and an optional next handler
in the chain.
Construct a new handler composed of a HandlerFunc with state and an optional next handler in the chain .
handler
HandlerFunc<S, T>
next
Option<Handler<S, T>>