Function diff_text 

pub fn diff_text(
    old_bytes: &[u8],
    old_label: &str,
    new_bytes: &[u8],
    new_label: &str,
) -> Result<String, Refusal>

The whole difference as text, one row a line in the fixed order: the API’s surface, the tests’ and a door’s that holds the text. Each label is what a refusal calls its file.