static inline void add_namespace_name(Array &out, xmlNsPtr ns) {
  String prefix = ns->prefix ? String((const char*)ns->prefix) :
                               String(empty_string);
  if (!out.exists(prefix)) {
    out.set(prefix, String((char*)ns->href, CopyString));
  }
}
static inline void add_namespace_name(Array &out, xmlNsPtr ns) {
  String prefix = ns->prefix ? String((const char*)ns->prefix) :
                               String(empty_string);
  if (!out.exists(prefix)) {
    out.set(prefix, String((char*)ns->href, CopyString));
  }
}