def update(self, friendly_name=values.unset, certificate=values.unset,
               private_key=values.unset, sandbox=values.unset, api_key=values.unset,
               secret=values.unset):
        """
        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
        """
        return self._proxy.update(
            friendly_name=friendly_name,
            certificate=certificate,
            private_key=private_key,
            sandbox=sandbox,
            api_key=api_key,
            secret=secret,
        )
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