#### buffered_read_stream::async_write_some

Start an asynchronous write. The data being written must be valid for the lifetime of the asynchronous operation.

    template<
        typename ConstBufferSequence,
        typename WriteHandler = DEFAULT>
    DEDUCED async_write_some(
        const ConstBufferSequence & buffers,
        WriteHandler && handler = DEFAULT);

###### Completion Signature

    void(asio::error_code, std::size_t)