def METHOD_NAME():
    # Check all locale IDs are uniques.
    all_ids = localedata.locale_identifiers()
    assert len(all_ids) == len(set(all_ids))
    # Check locale IDs don't collide after lower-case normalization.
    lower_case_ids = list(map(methodcaller('lower'), all_ids))
    assert len(lower_case_ids) == len(set(lower_case_ids))