void strIter(SV* code, SV* string)  {
    dSP;
    STRLEN i;
    char* src = SvPV(string, i);
    char* dst;
    SV* c;

    c = newSVpvn(" ", 1);
    dst = SvPVX(c);

    SAVE_DEFSV;
    DEFSV_set(c);

    while (i--) {
        *dst = *(src++);
        PUSHMARK(SP);
        call_sv(code, G_NOARGS | G_VOID | G_DISCARD);
    }
}