Function map_parser

pub fn map_parser<'a, 'arn: 'a, 'grm: 'arn, O, P, E: ParseError>(
    p: impl Parser<'arn, 'grm, O, E> + 'a,
    f: &'a impl Fn(O) -> P,
) -> impl Parser<'arn, 'grm, P, E> + 'a