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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_membership_listener(self, member_added=None, member_removed=None, fire_for_existing=False):
 """ Helper method for adding membership listeners :param member_added: (Function), Function to be called when a member is added, in the form of f(member) (optional). :param member_removed: (Function), Function to be called when a member is removed, in the form of f(member) (optional). :param fire_for_existing: if True, already existing members will fire member_added event (optional). :return: `self` for cascading configuration """

        self.membership_listeners.append((member_added, member_removed, fire_for_existing))
        return self