@Nullable
  private PyStringLiteralExpression addPredefinedMethodDoc(@NotNull PyFunction fun, @NotNull String methodName) {
    final PyClassType objectType = PyBuiltinCache.getInstance(fun).getObjectType(); // old- and new-style classes share the __xxx__ stuff
    if (objectType != null) {
      final PyClass objectClass = objectType.getPyClass();
      final PyFunction predefinedMethod = objectClass.findMethodByName(methodName, false, null);
      if (predefinedMethod != null) {
        final PyStringLiteralExpression predefinedDocstring = getEffectiveDocStringExpression(predefinedMethod);
        final String predefinedDoc = predefinedDocstring != null ? predefinedDocstring.getStringValue() : null;
        if (predefinedDoc != null && !predefinedDoc.isEmpty()) {
          mySectionsMap.get(PyPsiBundle.message("QDOC.copied.from")).append(PyPsiBundle.message("QDOC.built.in.description"));
          myContent.append(safeRunFormatterService(fun, predefinedDoc));
        }
        return predefinedDocstring;
      }
    }
    return null;
  }
@Nullable
  private PyStringLiteralExpression addPredefinedMethodDoc(@NotNull PyFunction fun, @NotNull String methodName)