docs: def addModel(self, moduleName, modelName, model):
          """
          Add a model instance to the application model pool.
  
          :param moduleName: <str> module name in which the model is located
          :param modelName: <str> model name
          :param model: <object> model instance
          :return: <void>
          """
          modelIdentifier = "{}.{}".format(moduleName, modelName)
          if modelIdentifier not in self._models:
              self._models[modelIdentifier] = model
          else:
              message = "Application - addModel() - " \
                        "A model with the identifier {} already exists." \
                        .format(modelIdentifier)
              raise Exception(message)