Return the intermediate representation of the diff.

def _make_diff(self, correct, given):
        """Return the intermediate representation of the diff."""
        dmp = DMP()
        dmp.Diff_Timeout = 4
        text1, text2, array = dmp.diff_linesToChars(correct, given)
        diffs = dmp.diff_main(text1, text2)
        dmp.diff_cleanupSemantic(diffs)
        dmp.diff_charsToLines(diffs, array)
        return list(dmp_to_mdiff(diffs))