Return a Submission object for the given url or submission_id.

        :param comment_limit: The desired number of comments to fetch. If <= 0
            fetch the default number for the session's user. If None, fetch the
            maximum possible.
        :param comment_sort: The sort order for retrieved comments. When None
            use the default for the session's user.
        :param params: Dictionary containing extra GET data to put in the url.

def get_submission(self, url=None, submission_id=None, comment_limit=0,
                       comment_sort=None, params=None):
        """Return a Submission object for the given url or submission_id.

        :param comment_limit: The desired number of comments to fetch. If <= 0
            fetch the default number for the session's user. If None, fetch the
            maximum possible.
        :param comment_sort: The sort order for retrieved comments. When None
            use the default for the session's user.
        :param params: Dictionary containing extra GET data to put in the url.

        """
        if bool(url) == bool(submission_id):
            raise TypeError('One (and only one) of id or url is required!')
        if submission_id:
            url = urljoin(self.config['comments'], submission_id)
        return objects.Submission.from_url(self, url,
                                           comment_limit=comment_limit,
                                           comment_sort=comment_sort,
                                           params=params)