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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_notebook_node(self):                   # pragma: no cover
        "Load captured notebook node"
        size = len(self._notebook_data)
        if size == 0:
            raise Exception("Captured buffer size for notebook node is zero.")
        node = reader.reads(self._notebook_data)
        self.nbversion = reader.get_version(node)
        return node