Return a diff between two branches/commits.

        Args:
            from_(str): Source branch/SHA
            to(str): Destination branch/SHA
            **kwargs: Extra options to send to the server (e.g. sudo)

        Raises:
            GitlabAuthenticationError: If authentication is not correct
            GitlabGetError: If the server failed to perform the request

        Returns:
            str: The diff

def repository_compare(self, from_, to, **kwargs):
        """Return a diff between two branches/commits.

        Args:
            from_(str): Source branch/SHA
            to(str): Destination branch/SHA
            **kwargs: Extra options to send to the server (e.g. sudo)

        Raises:
            GitlabAuthenticationError: If authentication is not correct
            GitlabGetError: If the server failed to perform the request

        Returns:
            str: The diff
        """
        path = '/projects/%s/repository/compare' % self.get_id()
        query_data = {'from': from_, 'to': to}
        return self.manager.gitlab.http_get(path, query_data=query_data,
                                            **kwargs)