<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_approval_by_id(self, issue_id_or_key, approval_id):
 """ Get an approval for a given approval ID :param issue_id_or_key: str :param approval_id: str :return: """

        url = 'rest/servicedeskapi/request/{0}/approval/{1}'.format(issue_id_or_key, approval_id)

        return self.get(url, headers=self.experimental_headers)