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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 get_filter(self):
 """ Returns the filter applie to this column """

        q = self.q().select('name').expand('filter')
        response = self.session.get(self.build_url(''), params=q.as_params())
        if not response:
            return None
        data = response.json()
        return data.get('criteria', None)