Cocerning此函数的堆栈图

Question

def factorial(n):
    space = ' ' * (4*n)
    print (space, 'factorial', n)
    if n == 0 :
        print(space, 'returning 1')
        return 1
    else:
        recurse = factorial(n-1)
        result = n * recurse
        print(space, 'returning', result)
        return result

factorial(5)

结果是，

                     factorial 5
                 factorial 4
             factorial 3
         factorial 2
     factorial 1
 factorial 0
 returning 1
     returning 1
         returning 2
             returning 6
                 returning 24
                     returning 120

无法理解我们如何从第5阶段和第4阶段开始。 to＆＃34; factorial 4＆＃34;在下一行。