def get_when_exploration_rated(user_id, exploration_id):
 exp_user_data_model = user_models.ExplorationUserDataModel.get(user_id, exploration_id)
 return (exp_user_data_model.rated_on if exp_user_data_model else None)

def get_when_exploration_rated ( user_id , exploration_id ) : exp_user_data_model = user_models . ExplorationUserDataModel . get ( user_id , exploration_id ) return ( exp_user_data_model . rated_on if exp_user_data_model else None )
fetches the datetime the exploration was last rated by this user .