user: I've been on a classic film binge lately and have a few iconic movies lined up for my next movie night. My cousin is staying over, so I need to ensure the films are appropriate for us to watch together. Could you check the age ratings for 'Pulp Fiction', 'The Godfather', 'Schindler's List', and 'The Dark Knight'?

Available functions:
name: get_movie_rating
description: Fetches the age rating of a movie from the OMDB API.
parameters: type: dict
properties: movie_name: type: string
description: The name of the movie.
required: movie_name