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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 server_version(self) -> Version: """Get the version of Livy running on the server."""

        if self._server_version_cache is None:
            data = self._client.get("/version")
            self._server_version_cache = Version(data["version"])
        return self._server_version_cache