fn fill_between(
    prev_lhs: Option<LineNumber>,
    next_lhs: Option<LineNumber>,
    prev_rhs: Option<LineNumber>,
    next_rhs: Option<LineNumber>
) -> Vec<(Option<LineNumber>, Option<LineNumber>)>Notable traits for Vec<u8, A>impl<A> Write for Vec<u8, A>where
    A: Allocator,