template<class ConstBufferSequence>
size_t buffer_size(const ConstBufferSequence& buffers) noexcept;
Returns: The total size of all buffers in the sequence, as if computed as follows:
size_t total_size = 0; auto i = std::experimental::net::buffer_sequence_begin(buffers); auto end = std::experimental::net::buffer_sequence_end(buffers); for (; i != end; ++i){ const_buffer b(*i); total_size += b.size(); } return total_size;