stem = py_file.stem
            for suffix in ("_py39", "_py310"):
                if suffix in stem:
                    an_stem = stem.replace(suffix, f"_an{suffix}", 1)
                    break
            else:
                an_stem = f"{stem}_an"
            counterpart = full_path_str.replace(f"/{stem}.", f"/{an_stem}.")

/**
 * Manages a dictionary file for stemmer overrides.
 * This class handles reading, parsing, and updating files that contain
 * stemmer override rules, where each rule maps an input word to an
 * output stem. The file format is expected to be `input => output`.
 *
 * The class provides methods for retrieving, adding, updating, and
 * deleting stemmer override items, as well as reloading the dictionary
 * from its source file.
 */