Function optional

src/licensedcode/_vendor/attr/validators.py:277–292

A validator that makes an attribute optional. An optional attribute is one which can be set to ``None`` in addition to satisfying the requirements of the sub-validator. :param validator: A validator (or a list of validators) that is used for non-``None`` values. :type

(validator)

def optional(validator):
    """
    A validator that makes an attribute optional.  An optional attribute is one
    which can be set to ``None`` in addition to satisfying the requirements of
    the sub-validator.

    :param validator: A validator (or a list of validators) that is used for
        non-``None`` values.
    :type validator: callable or `list` of callables.

    .. versionadded:: 15.1.0
    .. versionchanged:: 17.1.0 *validator* can be a list of validators.
    """
    if isinstance(validator, list):
        return _OptionalValidator(_AndValidator(validator))
    return _OptionalValidator(validator)


@attrs(repr=False, slots=True, hash=True)