code: def ledger(self, ledger_id):
          
          endpoint = '/ledgers/{ledger_id}'.format(ledger_id=ledger_id)
          return self.query(endpoint)
docs: The ledger details endpoint provides information on a single ledger.
  
          `GET /ledgers/{sequence}
          <https://www.stellar.org/developers/horizon/reference/endpoints/ledgers-single.html>`_
  
          :param int ledger_id: The id of the ledger to look up.
          :return: The details of a single ledger.
          :rtype: dict