Function buffer_size

3rd/asio-1.24.0/include/asio/buffer.hpp:553–557

template <typename Iterator>
inline std::size_t buffer_size(one_buffer,
    Iterator begin, Iterator) ASIO_NOEXCEPT
{
  return const_buffer(*begin).size();
}

template <typename Iterator>
inline std::size_t buffer_size(multiple_buffers,