Function async_write_some

include/boost/asio/basic_writable_pipe.hpp:558–568

      BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code,
        std::size_t)) WriteToken = default_completion_token_t<executor_type>>
  auto async_write_some(const ConstBufferSequence& buffers,
      WriteToken&& token = default_completion_token_t<executor_type>())
    -> decltype(
      async_initiate<WriteToken,
        void (boost::system::error_code, std::size_t)>(
          declval<initiate_async_write_some>(), token, buffers))
  {
    return async_initiate<WriteToken,
      void (boost::system::error_code, std::size_t)>(
        initiate_async_write_some(this), token, buffers);
  }

private:
  // Disallow copying and assignment.