input: Write a python function to count the number of comments for a given post.
  assert count_comments(1) == 1
  assert count_comments(2) == 0
  assert count_comments(3) == 5
output: def count_comments(post_id):
      # Assuming we have a dictionary to simulate a database of comments
      comments_db = {
          1: ['Great post!'],
          2: [],
          3: ['Nice article', 'Thanks for sharing', 'Informative', 'Well written', 'Good read']
      }
      
      return len(comments_db.get(post_id, []))