private FunctionNode getNodeByIndex(int index) {
        if (index < 0) throw new FunctionPointIndexOutOfBoundsException("Incorrect index");
        if (currentIndex <= index) {
            while (currentIndex < index) {
                currentFunctionNode = currentFunctionNode.pointNext;
                ++currentIndex;
            }
        } else {
            while (index < currentIndex) {
                currentFunctionNode = currentFunctionNode.pointPrev;
                --currentIndex;
            }
        }
        return currentFunctionNode;
    }