def update(self, friendly_name=values.unset, certificate=values.unset,<EOL>private_key=values.unset, sandbox=values.unset, api_key=values.unset,<EOL>secret=values.unset):
return self._proxy.update(<EOL>friendly_name=friendly_name,<EOL>certificate=certificate,<EOL>private_key=private_key,<EOL>sandbox=sandbox,<EOL>api_key=api_key,<EOL>secret=secret,<EOL>)<EOL>
Update the CredentialInstance

:param unicode friendly_name: A string to describe the resource
:param unicode certificate: [APN only] The URL-encoded representation of the certificate
:param unicode private_key: [APN only] URL-encoded representation of the private key
:param bool sandbox: [APN only] Whether to send the credential to sandbox APNs
:param unicode api_key: [GCM only] The `Server key` of your project from Firebase console under Settings / Cloud messaging
:param unicode secret: [FCM only] The `Server key` of your project from Firebase console under Settings / Cloud messaging

:returns: Updated CredentialInstance
:rtype: twilio.rest.notify.v1.credential.CredentialInstance