Adds a comment to the post provided.

def add_comment(self, post=None, name=None, email=None, pub_date=None,
                    website=None, body=None):
        """
        Adds a comment to the post provided.
        """
        if post is None:
            if not self.posts:
                raise CommandError("Cannot add comments without posts")
            post = self.posts[-1]
        post["comments"].append({
            "user_name": name,
            "user_email": email,
            "submit_date": pub_date,
            "user_url": website,
            "comment": body,
        })