def hanoi(n, source, helper, target):
print("hanoi( ", n, source, helper, target, " called")
if n > 0:
hanoi(n - 1, source, target, helper)
if source[0]:
disk = source[0].pop()
print("moving " + str(disk) + " from " + source[1] + " to " + target[1])
target[0].append(disk)
hanoi(n - 1, helper, source, target)
source = ([4,3,2,1], "source")
target = ([], "target")
helper = ([], "helper")
hanoi(len(source[0]),source,helper,target)
print(source, helper, target)