def deprecated(value):
    if value is None:
        return

    if is_sequence(value) and not value:
        return

    fmt = "The use of this field has been deprecated. Received '{0}' object."
    msg = fmt.format(type(value).__name__)
    warnings.warn(msg)
Raises a Python UserWarning if `value` is not None.
dataset/ETHPy150Open STIXProject/python-stix/stix/utils/deprecated.py/deprecated