pub(crate) fn color_positions(
    side: Side,
    background: BackgroundColor,
    syntax_highlight: bool,
    file_format: &FileFormat,
    positions: &[MatchedPos]
) -> Vec<(SingleLineSpan, Style)>Notable traits for Vec<u8, A>impl<A> Write for Vec<u8, A>where
    A: Allocator,