public void ns(String prefix, String uri, int ln) {
        if (nv != null && nv instanceof AxmlVisitor) {
            ((AxmlVisitor) nv).ns(prefix, uri, ln);
        }
    }
create a ns

@param prefix
@param uri
@param ln
android/third_party/apkbuilder/src/main/java/pxb/android/axml/AxmlVisitor.java