input: Write a python function to return a list of articles that have links to other articles.
  assert linked_articles(["Java", "JavaScript", "Python", "C++", "C#"]) == ["Java", "JavaScript", "Python", "C++", "C#"]
  assert linked_articles(["Python", "Java"]) == ["Python", "Java"]
  assert linked_articles(["C++", "C#", "Ruby"]) == ["C++", "C#", "Ruby"]
output: def linked_articles(articles):
      # Assuming all articles have links to other articles for this mock function
      return articles