void checkElementTypes(@NotNull final Iterable<T> elements) {
    for (final PyElement pyElement : elements) {
      Preconditions.checkArgument(myExpectedClass.isAssignableFrom(pyElement.getClass()),
                                  String.format("Manager %s expected %s but got %s", this, myExpectedClass, pyElement));
    }
  }
void checkElementTypes(@NotNull final Iterable<T> elements)