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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 push_subscription_update(self, follow_events=None, favourite_events=None, reblog_events=None, mention_events=None):
 """ Modifies what kind of events the app wishes to subscribe to. Returns the updated `push subscription dict`_. """

        params = {}
        
        if follow_events != None:
            params['data[alerts][follow]'] = follow_events
        
        if favourite_events != None:
            params['data[alerts][favourite]'] = favourite_events
            
        if reblog_events != None:
            params['data[alerts][reblog]'] = reblog_events
            
        if mention_events != None:
            params['data[alerts][mention]'] = mention_events
            
        return self.__api_request('PUT', '/api/v1/push/subscription', params)