Function anchored_unified_diff 

pub fn anchored_unified_diff(
    old_content: &str,
    new_content: &str,
    old_path: &str,
    new_path: &str,
    context_lines: usize,
    anchors: &[String],
) -> String

Compute a unified diff with anchored lines.

Anchored lines that appear exactly once in both old and new content are forced to match, splitting the diff into segments around those anchor points. This produces diffs where the anchored text stays as context and surrounding lines are shown as additions/removals.