<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add_webhook(self, name, metadata=None):
 """ Adds a webhook to this policy. """

        return self.manager.add_webhook(self.scaling_group, self, name,
                metadata=metadata)