code: def _issue_cert(self, domain):
          
          def errback(failure):
              # Don't fail on some of the errors we could get from the ACME
              # server, rather just log an error so that we can continue with
              # other domains.
              failure.trap(txacme_ServerError)
              acme_error = failure.value.message
  
              if acme_error.code in ['rateLimited', 'serverInternal',
                                     'connection', 'unknownHost']:
                  # TODO: Fire off an error to Sentry or something?
                  self.log.error(
                      'Error ({code}) issuing certificate for "{domain}": '
                      '{detail}', code=acme_error.code, domain=domain,
                      detail=acme_error.detail)
              else:
                  # There are more error codes but if they happen then something
                  # serious has gone wrong-- carry on error-ing.
                  return failure
  
          d = self.txacme_service.issue_cert(domain)
          return d.addErrback(errback)
docs: Issue a certificate for the given domain.