#implementation of function “Iterative_deepening_DFS”def Iterative_deepening_DFS(self,goalState):    queueNodesPopped =0    queueMaxLen = 1        for depthLimitIn in range(40):        queue = self        depthOfQueue = 0        pathCostQueue = 0        alreadyVisitedNodes = set()                while queue:            if len(queue) > queueMaxLen :                queueMaxLen = len(queue)            currentNodeOfQueue = queue.pop(0)            queueNodesPopped += 1            currentDepthQueue = depthOfQueue.pop(0)            currentPathCostOfQueue = pathCostQueue.pop(0)            alreadyVisitedNodes.add(tuple(currentNodeOfQueue.state.reshape(1,9)0))                        if np.array_equal(currentNodeOfQueue.state,goalState):                currentNodeOfQueue.printPathToGoal()                                print (‘Time performance to get to the goal’, str(queueNodesPopped), ‘are the nodes pooped off the queue.’)                print (‘Time spent to get to the goal:% 0.2fs’ %(time.time()-start))                            else:                if currentNodeOfQueue < depthLimitIn:                                        if currentNodeOfQueue.isMovingDownValid() :                        destinationState,upValuePosition  = currentNodeOfQueue.isMovingDownValid()                        if tuple(destinationState.reshape(1,9)0) not in alreadyVisitedNodes:                            currentNodeOfQueue.moveDownDirection = Node(state=destinationState,parent=currentNodeOfQueue,actionResulted='down',depthValue=currentDepthQueue+1,stepCost=upValuePosition,pathCost=currentPathCostOfQueue+upValuePosition,heuristicCost=0)                            queue.insert(0,currentNodeOfQueue.moveDownDirection)                            depthOfQueue.insert(0,currentDepthQueue+1)                            pathCostQueue.insert(0,currentPathCostOfQueue+upValuePosition)                                        if currentNodeOfQueue.isMovingRightValid() :                        destinationState,leftValuePosition  = currentNodeOfQueue.isMovingRightValid()                        if tuple(destinationState.reshape(1,9)0) not in alreadyVisitedNodes:                            currentNodeOfQueue.moveRightDirection = Node(state=destinationState,parent=currentNodeOfQueue,actionResulted='Right',depthValue=currentDepthQueue+1,stepCost=leftValuePosition,pathCost=currentPathCostOfQueue+leftValuePosition,heuristicCost=0)                            queue.insert(0,currentNodeOfQueue.moveRightDirection)                            depthOfQueue.insert(0,currentDepthQueue+1)                            pathCostQueue.insert(0,currentPathCostOfQueue+leftValuePosition)                                                if currentNodeOfQueue.isMovingUpValid() :                        destinationState,lowerValuePosition  = currentNodeOfQueue.isMovingUpValid()                        if tuple(destinationState.reshape(1,9)0) not in alreadyVisitedNodes:                            currentNodeOfQueue.moveUpDirection = Node(state=destinationState,parent=currentNodeOfQueue,actionResulted='up',depthValue=currentDepthQueue+1,stepCost=lowerValuePosition,pathCost=currentPathCostOfQueue+lowerValuePosition,heuristicCost=0)                            queue.insert(0,currentNodeOfQueue.moveUpDirection)                            depthOfQueue.insert(0,currentDepthQueue+1)                            pathCostQueue.insert(0,currentPathCostOfQueue+lowerValuePosition)                                                if currentNodeOfQueue.isMovingLeftValid() :                        destinationState,rightValuePosition  = currentNodeOfQueue.isMovingLeftValid()                        if tuple(destinationState.reshape(1,9)0) not in alreadyVisitedNodes:                            currentNodeOfQueue.moveLeftDirection = Node(state=destinationState,parent=currentNodeOfQueue,actionResulted='Left',depthValue=currentDepthQueue+1,stepCost=rightValuePosition,pathCost=currentPathCostOfQueue+rightValuePosition,heuristicCost=0)                            queue.insert(0,currentNodeOfQueue.moveLeftDirection)                            depthOfQueue.insert(0,currentDepthQueue+1)                            pathCostQueue.insert(0,currentPathCostOfQueue+rightValuePosition)