C++/CX, how to safely use new APIs but also run on older windows 10

I need my app to still run on the HoloLens. How do I do this

Code

      if(mStageReferenceFrame)
        mRenderer.reset(new Renderer(!HolographicDisplay::GetDefault()->IsOpaque, mStageReferenceFrame));
      else
        mRenderer.reset(new Renderer(!HolographicDisplay::GetDefault()->IsOpaque, mStationaryReferenceFrame));

Api HolographicDisplay::GetDefault()->IsOpaque only available on fall creators. How do I check that is is available before calling on my old HoloLens which crashes with Platform::ClassNotRegisteredException

I need to solve this problem before next weekend.