Anubis

I don't know if it is easy to do, but the goal of this keyword is to generate a message if a function definition has moved from one file to another, and the new definition has not be found by the compiler.

Thus the message will clearly tell to the user that to use the function, he has to read this new file.

Of course, the error message is displayed only if the function is used and the new definition isn't found.

On the old location, the definition has been removed. Only the declaration can be found (parameters and return type), associated with this keyword.

And we can do the same thing with types.