swift

08220881 - [AutoDiff] Add binary version of `differentiableFunction`. (#21954)

[AutoDiff] Add binary version of `differentiableFunction`. (#21954) Add a new version of `differentiableFunction` that supports binary functions. Add runtime tests. Note: type-checker errors regarding closures (like the arguments to `differentiableFunction`) are inscrutable and often don't highlight actual errors in source code. This is a significant hurdle for usability.