code: @SuppressWarnings("unused") // called through reflection by RequestServer
    public FramesV3 column(int version, FramesV3 s) { // TODO: should return a Vec schema
      Frame frame = getFromDKV("key", s.frame_id.key());
  
      Vec vec = frame.vec(s.column);
      if (null == vec)
        throw new H2OColumnNotFoundArgumentException("column", s.frame_id.toString(), s.column);
  
      Vec[] vecs = { vec };
      String[] names = { s.column };
      Frame new_frame = new Frame(names, vecs);
      s.frames = new FrameV3[1];
      s.frames[0] = new FrameV3(new_frame);
      ((FrameV3)s.frames[0]).clearBinsField();
      return s;
    }
docs: Return a single column from the frame.