class ModelWithIndexedBool(Model): active = props.Bool(indexed=True)
class Bird(Animal): flightless = props.Bool(default=False)
class Animal(Model, poly=True): endangered = props.Bool(default=False) birthday = props.DateTime(indexed=True, auto_now_add=True)
class ConditionsModelIsNotNone(Model): b = props.Bool(optional=True, indexed_if=conditions.is_not_none)
class ConditionsModelIsFalse(Model): b = props.Bool(indexed_if=conditions.is_false)
class ConditionsModelIsTrue(Model): b = props.Bool(indexed_if=conditions.is_true)