Function cut::offer_case

pub fn offer_case<N, C, A, Row1, Row2>(
    N, 
    cont: PartialSession<C, A>
) -> PartialSession<C, InternalChoice<Row1>> where
    C: Context,
    A: Protocol,
    Row1: 'static + Send + ToRow<Row = Row2>,
    Row2: 'static + Send + RowCon,
    N: Prism<Row2, Elem = A>,