pub fn upgrade_error<I, O, E1, E2, F>( f: F, ) -> impl FnMut(I) -> IResult<I, O, E2>where E1: ParseError<I>, E2: ParseError<I> + From<E1>, F: FnMut(I) -> IResult<I, O, E1>,
Apply combinator, automatically converts between errors if the underlying type supports it