#### buffered_read_stream::async_read_some

Start an asynchronous read. The buffer into which the data will be read must be valid for the lifetime of the asynchronous operation.

    template<
        typename MutableBufferSequence,
        typename ReadHandler = default_completion_token_t<executor_type>>
    DEDUCED async_read_some(
        const MutableBufferSequence & buffers,
        ReadHandler && handler = default_completion_token_t< executor_type >());

###### Completion Signature

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