code: def get_external_model(class_object):
      
      class_abstract = class_object.CodenerixMeta.abstract
      if class_abstract is not None:
          for class_related in class_object._meta.related_objects:
              if issubclass(class_related.related_model, class_abstract):
                  return class_related.related_model
      return None
docs: Given a class (class_object), it locates the related model (throught the codenerix abstract class)