Node leftNode = new Node(NodeType.OPERATOR, ">=");
leftNode.appendChildNode(inputNode);
leftNode.appendChildNode(lowerNode);
Node rightNode = new Node(NodeType.OPERATOR, "<=");
rightNode.appendChildNode(inputNode);
rightNode.appendChildNode(upperNode);
Node betweenNode = new Node(NodeType.OPERATOR, "&&");
betweenNode.appendChildNode(rightNode);
betweenNode.appendChildNode(leftNode);