code: static Frame toFrame(Vector v, Key key) {
      final int log_rows_per_chunk = Math.max(1, FileVec.DFLT_LOG2_CHUNK_SIZE - (int) Math.floor(Math.log(1) / Math.log(2.)));
      Vec vv = makeCon(0, v.size(), log_rows_per_chunk, false /* no rebalancing! */);
      Frame f = new Frame(key, new Vec[]{vv}, true);
      try( Vec.Writer vw = f.vecs()[0].open() ) {
        for (int r = 0; r < v.size(); ++r)
          vw.set(r, v.get(r));
      }
      DKV.put(key, f);
      return f;
    }
docs: Helper to convert a Vector into a Frame
  @param v Vector
  @param key Key for output Frame
  @return Reference to Frame (which is also in DKV)