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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 list(self, label=None, per_page=20, page=1):
 """ Get a list of identities that have been created :param per_page: The number of results per page returned :type per_page: int :param page: The page number of the results :type page: int :return: dict of REST API output with headers attached :rtype: :class:`~datasift.request.DictResponse` :raises: :class:`~datasift.exceptions.DataSiftApiException`, :class:`requests.exceptions.HTTPError` """


        params = {'per_page': per_page, 'page': page}

        if label:
            params['label'] = label

        return self.request.get('', params)