Don't require the `--structure` argument.
{
            char value[16];
            hash.get128(value);
            memcpy(dst, value, end - dst);
        }
        pos += 16;
        ++i;
    }
    for (size_t j = 0; j < size; ++j)
    {
        if (isWordCharASCII(src[j]))
        {
            static constexpr char word_chars[] = "_01234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
            dst[j] = word_chars[dst[j] % (sizeof(word_chars) - 1)];
        }
    }
}
static void transformUUID(const UUID & src_uuid, UUID & dst_uuid, UInt64 seed)
{
    const UInt128 & src = src_uuid.toUnderType();
    UInt128 & dst = dst_uuid.toUnderType();
    SipHash hash;
    hash.update(seed);
    hash.update(reinterpret_cast<const char *>(&src), sizeof(UUID));
    
    hash.get128(reinterpret_cast<char *>(&dst));
    dst.items[1] = (dst.items[1] & 0x1fffffffffffffffull) | (src.items[1] & 0xe000000000000000ull);
    dst.items[0] = (dst.items[0] & 0xffffffffffff0fffull) | (src.items[0] & 0x000000000000f000ull);
}
class FixedStringModel : public IModel