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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 append(self, node, dirty=True):
 """Add a new child node. Args: node (gkeepapi.Node):
 Node to add. dirty (bool):
 Whether this node should be marked dirty. """

        self._children[node.id] = node
        node.parent = self
        if dirty:
            self.touch()

        return node