Function combinedfun::tag

pub fn tag<'a, I, E, T: ?Sized>(
    tag: &'a T
) -> Parser<impl ParserImpl<I, Output = T::Output, Error = E> + 'a, I> where
    T: Tag<I>,
    E: TagError<'a, T, I>,
    I: Clone, 

Requires the input to start with the given subsequence/substring.