<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_bug_by_id(self, bug_id):
 """ Retrieves a single bug by it's Launchpad bug_id :param bug_id: The Launchpad id for the bug. """

        uri = '{base}/bugs/{bug_id}'.format(base=self.BASE_URI, bug_id=bug_id)
        resp = self._client.get(uri, model=models.Bug)

        return resp