fn add_ends(
matched_lines: &[(Option<LineNumber>, Option<LineNumber>)],
lhs_lines: &[&str],
rhs_lines: &[&str]
) -> Vec<(Option<LineNumber>, Option<LineNumber>)>Expand description
Extend matched_lines to include the leading and trailing lines
in the file.
This is useful when the file contains blank lines at the beginning or end. Those lines won’t have MatchedPos values associated with them, but we still want to match them up.