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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_chain(self, index):
 """Assemble and return the chain leading from a given node to the merkle root of this tree. """

        chain = []
        this = self.leaves[index]
        chain.append((this.val, 'SELF'))
        while this.p:
            chain.append((this.sib.val, this.sib.side))
            this = this.p
        chain.append((this.val, 'ROOT'))
        return chain