Function parse_simple_pat

fn parse_simple_pat<'a, F>(
    buf: &'a [u8],
    start_pat: &[u8],
    end_pat: &[u8],
    opts: ParseOpt,
    create_tt: F,
) -> Option<(MdTree<'a>, &'a [u8])>
where
    F: FnOnce(&'a str) -> MdTree<'a>,

The simplest kind of patterns: data within start and end patterns