(a) The following python code is the implementation of Best First Search for the graph as below, and the heuristic function to W,h(W), given in the table: \begin{tabular}{l} \hline graph ={ \\ 'P':[('Q',21), ('R',9), ('S',6)], \\ \# Part (a)(i): Add your code here \\ def bfs(start, target, graph, queue=[], visited=[]): \\ if start not in visited: \\ print(start) \\ visited.append(start) \\ queue=queue+[x for x in graph[start] if x [0][0] not in visited] \\ queue.sort(key=lambda x:x[1]) \\ if queue[0][0]=target: \\ print(queue[0][0]) \\ else: \\ processing=queue[0] \\ queue.remove(processing) \\ bfs(processing[0], target, graph, queue, visited) \\ bfs('P', 'W', graph) \end{tabular}