def update(self, callback_method=values.unset, callback_url=values.unset,<EOL>friendly_name=values.unset):
data = values.of({<EOL>'<STR_LIT>': callback_method,<EOL>'<STR_LIT>': callback_url,<EOL>'<STR_LIT>': friendly_name,<EOL>})<EOL>payload = self._version.update(<EOL>'<STR_LIT:POST>',<EOL>self._uri,<EOL>data=data,<EOL>)<EOL>return TriggerInstance(<EOL>self._version,<EOL>payload,<EOL>account_sid=self._solution['<STR_LIT>'],<EOL>sid=self._solution['<STR_LIT>'],<EOL>)<EOL>
Update the TriggerInstance

:param unicode callback_method: The HTTP method to use to call callback_url
:param unicode callback_url: The URL we call when the trigger fires
:param unicode friendly_name: A string to describe the resource

:returns: Updated TriggerInstance
:rtype: twilio.rest.api.v2010.account.usage.trigger.TriggerInstance