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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:
 async def load(self, node_id=None):
 """Load nodes from KLF 200, if no node_id is specified all nodes are loaded."""

        if node_id is not None:
            await self._load_node(node_id=node_id)
        else:
            await self._load_all_nodes()