OptionalTextPositionUnaryFunction
class OptionalTextPositionUnaryFunction<A, OA : ObservableValue<A>>(argA: OA, lambda: (A) -> TextPosition?) : UnaryFunction<TextPosition?, A, OA> , ObservableOptionalTextPosition
Boilerplate which avoids having to use generics.
Similar to TextPositionUnaryFunction, but the value can also be null.