code: def certificates(self):
          
          if self._certificates is None:
              self._certificates = CertificateList(self._version, fleet_sid=self._solution['sid'], )
          return self._certificates
docs: Access the certificates
  
          :returns: twilio.rest.preview.deployed_devices.fleet.certificate.CertificateList
          :rtype: twilio.rest.preview.deployed_devices.fleet.certificate.CertificateList