def METHOD_NAME(self, node, pk, sk):
    if node.type == node.EXP:
        print("public =>", node.getLeft(), "in pk?", pk.get(node.getLeft()))
        print("secret =>", node.getRight(), "in sk?", sk.get(node.getRight()))
    elif node.type == node.EQ:
        print("public =>", node.getLeft(), "in pk?", pk.get(node.getLeft()))
        self.METHOD_NAME(node.getRight(), pk, sk)
    elif node.type == node.AND:
        self.METHOD_NAME(node.getLeft(), pk, sk)
        self.METHOD_NAME(node.getRight(), pk, sk)
    else:
        return None
    return None