Given a class (class_object), a name for a method (method_name) and its arguments,
    it searchs for the method in the related model (throught the codenerix abstract class) and
    it executes that method or return None if no method is found.

def get_external_method(class_object, method_name, *args, **kwargs):
    """
    Given a class (class_object), a name for a method (method_name) and its arguments,
    it searchs for the method in the related model (throught the codenerix abstract class) and
    it executes that method or return None if no method is found.
    """
    related_model = get_external_model(class_object)
    if related_model is not None:
        f = getattr(related_model, method_name, None)
        if f:
            instance = related_model()
            return f(instance, *args, **kwargs)
        else:
            return None
    return None