@classmethod
def validate(cls, entity, new_value):
    """Validate a value for this attribute.

        This will be called by the blob when setting the value for this
        attribute, override it to perform any checks or sanitation.  This
        should either return a valid value for the attribute or raise an
        exception as to why the value is invalid.

        :param entity: The entity this attribute is on
        :param new_value: The potential value to validate
        :returns: The validated (and optionally sanitized) value

        """
    return new_value
