def validate_ok_for_update(update):
    validate_is_mapping("update", update)
    # Update can not be {}
    if not update:
        raise ValueError('update only works with $ operators')
    first = next(iter(update))
    if not first.startswith('$'):
        raise ValueError('update only works with $ operators')


# journal is an alias for j,
# wtimeoutms is an alias for wtimeout,
Tests defacl ch.
dataset/ETHPy150Open mongodb/mongo-python-driver/pymongo/common.py/validate_ok_for_update--crossover with--dataset/ETHPy150Open GoogleCloudPlatform/gsutil/gslib/tests/test_defacl.py/TestDefacl.testChangeDefaultAcl