def update(self, webhook_url=values.unset, friendly_name=values.unset,<EOL>reachability_webhooks_enabled=values.unset,<EOL>acl_enabled=values.unset):
data = values.of({<EOL>'<STR_LIT>': webhook_url,<EOL>'<STR_LIT>': friendly_name,<EOL>'<STR_LIT>': reachability_webhooks_enabled,<EOL>'<STR_LIT>': acl_enabled,<EOL>})<EOL>payload = self._version.update(<EOL>'<STR_LIT:POST>',<EOL>self._uri,<EOL>data=data,<EOL>)<EOL>return ServiceInstance(self._version, payload, sid=self._solution['<STR_LIT>'], )<EOL>
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