Get data usage information.

        Returns:
            (dict): A dictionary representing different resource categories
            and their respective data usage.

        Raises:
            :py:class:`docker.errors.APIError`
                If the server returns an error.

def df(self):
        """
        Get data usage information.

        Returns:
            (dict): A dictionary representing different resource categories
            and their respective data usage.

        Raises:
            :py:class:`docker.errors.APIError`
                If the server returns an error.
        """
        url = self._url('/system/df')
        return self._result(self._get(url), True)