OptionalOrientationBinaryFunction
class OptionalOrientationBinaryFunction<A, OA : ObservableValue<A>, B, OB : ObservableValue<B>>(argA: OA, argB: OB, lambda: (A, B) -> Orientation?) : BinaryFunction<Orientation?, A, OA, B, OB> , ObservableOptionalOrientation
Boilerplate which avoids having to use generics.
Similar to OrientationBinaryFunction, but the value can also be null.