def quicksort(t):
    if t == []:
        return []
    else:
        pivot = t[0]
    t1 = []
    t2 = []
    for x in t[1:]:
        print(x, pivot)
        if x < pivot:
            t1.append(x)
        else:
            t2.append(x)
        return quicksort(t1) + [pivot] + quicksort(t2)

if __name__=="__main__": 
    quicksort([1 ,4, 5])