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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 diff(self, container):
 """ Inspect changes on a container's filesystem. Args: container (str):
 The container to diff Returns: (str) Raises: :py:class:`docker.errors.APIError` If the server returns an error. """

        return self._result(
            self._get(self._url("/containers/{0}/changes", container)), True
        )