Function ensure_data

library/include/modules/Persistence.h:111–117

            return (data_size() >= off + sz);
        }
        void ensure_data(size_t off, size_t sz = 0)
        {
            if (data_size() < off + sz)
            {
                val().resize(off + sz, '\x01');
            }
        }
        template<size_t N>
        uint8_t (&pdata(size_t off))[N]
        {