import os
import git

def download_github_repo(repo_url, repo_dir):
    if os.path.exists(repo_dir):
        print(f"Repository {repo_dir} already exists. Pulling latest changes.")
        repo = git.Repo(repo_dir)
        repo.remotes.origin.pull()
    else:
        print(f"Cloning repository from {repo_url} to {repo_dir}.")
        git.Repo.clone_from(repo_url, repo_dir)