  int DoWrite(std::unique_ptr<WriteWrap>& w,
              uv_buf_t* bufs,
              size_t count,
              uv_stream_t* send_handle) override {
    return UV_ENOSYS;  // Not implemented (yet).
  }
  int DoWrite(std::unique_ptr<WriteWrap>& w,
              uv_buf_t* bufs,
              size_t count,
              uv_stream_t* send_handle) override {
    return UV_ENOSYS;   
  }