assertNoneType(new NFor(null, null, null, null));
assertNoneType(new NFunctionDef(null, null, null, null, null, null));
assertNoneType(new NGeneratorExp(null, null));
assertNoneType(new NGlobal(null));
assertNoneType(new NIf(null, null, null));
assertNoneType(new NIfExp(null, null, null));
assertNoneType(new NImport(null));
assertNoneType(new NImportFrom(null, null, null));
assertNoneType(new NIndex(null));
assertNoneType(new NKeyword(null, null));
assertNoneType(new NLambda(null, null, null, null, null));