user: I'm having a Tarantino movie marathon tonight and want to make sure I've got my facts straight for the trivia session with my friends. Can you fetch me the directors for the movies 'Pulp Fiction,' 'Reservoir Dogs,' 'Kill Bill,' and 'Django Unchained'? I'll need this info to impress the gang.

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