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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def operation(self, op_id):
 """The operation details endpoint provides information on a single operation. `GET /operations/{id} <https://www.stellar.org/developers/horizon/reference/endpoints/operations-single.html>`_ :param id op_id: The operation ID to get details on. :return: Details on a single operation. :rtype: dict """

        endpoint = '/operations/{op_id}'.format(op_id=op_id)
        return self.query(endpoint)