Would you put (these two) help method declarations into the header file?

In general? In this specific case?

As `lib.h` is included as the header file for the `d3d9.cpp`, `d3d10.cpp`, `dxgi.cpp` as well it’d be an `extern` declaration, like the `IsFnInModule` function.
Currently these two helper methods are not used elsewhere though. They are specific to the (main) lib logic of `lib.cpp`.