}
    
    char *ZstrFindSubstring(const char *haystack, const char *needle) {
        if (!haystack || !needle) {
            LOG_FATAL("Invalid arguments");

    
        while (prev <= end) {
            const char *next = ZstrFindSubstring(prev, key);
            if (next) {
                StrIter si = {.data = (char *)prev, .length = next - prev, .pos = 0, .alignment = 1};

            const char *end = s->data + s->length;
            while (prev <= end) {
                const char *next = ZstrFindSubstring(prev, key);
                if (next) {
                    Str tmp = StrInitFromCstr(prev, next - prev);

    /// FAILURE : NULL
    ///
    #define StrFindStr(str, key) ZstrFindSubstring((str)->data, (key)->data)
    
    ///

    /// FAILURE : NULL
    ///
    #define StrFindZstr(str, key) ZstrFindSubstring((str)->data, (key))
    
    ///