Function lip::pair

pub fn pair<'a, P1, P2, R1, R2, S: Clone + 'a>(
    parser1: P1, 
    parser2: P2
) -> impl Parser<'a, (R1, R2), S> where
    P1: Parser<'a, R1, S>,
    P2: Parser<'a, R2, S>, 

Pair up two parsers. Run the left parser, then the right, and last combine both outputs into a tuple.