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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 drop(self):
 """ Remove this node from the taxonomy, maintaining child subtrees by adding them to the node's parent, and moving sequences at this node to the parent. Not valid for root node. """

        if self.is_root:
            raise ValueError("Cannot drop root node!")

        parent = self.parent
        for child in self.children:
            child.parent = parent
            parent.children.add(child)
        self.children = set()

        parent.sequence_ids.update(self.sequence_ids)
        self.sequence_ids = set()

        parent.remove_child(self)