// Ensure op_denylist is non null
  if (!py_denylist) {
    return 0;
  }
  if (PyList_Check(py_denylist)) {
    for (int i = 0; i < PyList_GET_SIZE(py_denylist); ++i) {
      PyObject* value = PyList_GetItem(py_denylist, i);
      char* str_buf;
      Py_ssize_t length;
      if (ConvertFromPyString(value, &str_buf, &length) == -1) {
        return -1;
      }
      string_set->emplace(str_buf, length);
    }