[docs]defget_ball_ball_model(model:Optional[BallBallModel]=None,params:ModelArgs={})->BallBallCollisionStrategy:"""Returns a ball-ball collision model Args: model: An Enum specifying the desired model. If not passed, :class:`FrictionlessElastic` is passed with empty params. params: A mapping of parameters accepted by the model. Returns: An instantiated model that satisfies the :class:`BallBallCollisionStrategy` protocol. """ifmodelisNone:returnFrictionlessElastic()return_ball_ball_models[model](**params)