code: def update(self, webhook_url=values.unset, friendly_name=values.unset,
                 reachability_webhooks_enabled=values.unset,
                 acl_enabled=values.unset):
          
          data = values.of({
              'WebhookUrl': webhook_url,
              'FriendlyName': friendly_name,
              'ReachabilityWebhooksEnabled': reachability_webhooks_enabled,
              'AclEnabled': acl_enabled,
          })
  
          payload = self._version.update(
              'POST',
              self._uri,
              data=data,
          )
  
          return ServiceInstance(self._version, payload, sid=self._solution['sid'], )
docs: Update the ServiceInstance
  
          :param unicode webhook_url: A URL that will receive event updates when objects are manipulated.
          :param unicode friendly_name: Human-readable name for this service instance
          :param bool reachability_webhooks_enabled: True or false - controls whether this instance fires webhooks when client endpoints connect to Sync
          :param bool acl_enabled: true or false - determines whether token identities must be granted access to Sync objects via the Permissions API in this Service.
  
          :returns: Updated ServiceInstance
          :rtype: twilio.rest.sync.v1.service.ServiceInstance