char c2    = low < 10 ? '0' + low : is_caps ? 'A' + (low - 10) : 'a' + (low - 10);
    char cs[3] = {'\\', c1, c2};
    StrPushBackCstr(o, cs, 3);
    }
    vs++;

    ssize_t n = read(rfd, tmpbuf, 1023);
    if (n > 0) {
    StrPushBackCstr(buf, tmpbuf, n);
    total_read += n;
    } else if (n == 0) {

    }
    
    StrPushBackCstr(buf, tmpbuf, bytes_read);
    total_read += bytes_read;
    }

    // Test StrPushBackCstr function
    bool test_str_push_back_cstr(void) {
    WriteFmt("Testing StrPushBackCstr\n");
    
    Str s = StrInitFromZstr("Hello");

    
    // Push a string at the back
    StrPushBackCstr(&s, " World", 6);
    
    // Check that the string was inserted correctly

    /// FAILURE : NULL
    ///
    #define StrPushBackZstr(str, zstr) StrPushBackCstr((str), (zstr), strlen((zstr)))
    
    ///

    char *cstr = generate_cstring(data, offset, size, 20);
    if (cstr) {
    StrPushBackCstr(str, cstr, strlen(cstr));
    free(cstr);
    }

    char *cstr = generate_cstring(data, offset, size, 20);
    if (cstr) {
    StrPushBackCstr(str, cstr, strlen(cstr));
    free(cstr);
    }