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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 is_tuple(node):
 """Does the node represent a tuple literal?"""

    if isinstance(node, Node) and node.children == [LParen(), RParen()]:
        return True
    return (isinstance(node, Node)
            and len(node.children) == 3
            and isinstance(node.children[0], Leaf)
            and isinstance(node.children[1], Node)
            and isinstance(node.children[2], Leaf)
            and node.children[0].value == u"("
            and node.children[2].value == u")")