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