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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_graph_by_name_version(self, name: str, version: str) -> Optional[BELGraph]: """Load the BEL graph with the given name, or allows for specification of version."""

        network = self.get_network_by_name_version(name, version)

        if network is None:
            return

        return network.as_bel()