`module UnixDiff : sig ... end`
`module VISIBLE_FOR_TESTING_DO_NOT_USE_DIRECTLY : sig ... end`
`val parse_unix_diff : string ‑> int list`

Given a difference between two files, return the relevant lines in the new file; a line is relevant when a change took place in it, or nearby. To generate a valid input for this parser, use unix-diff command with the following formatter arguments: diff --unchanged-line-format="U" --old-line-format="O" --new-line-format="N" File1 File2