适用递归函数调试的一段代码

def ourSum(lower, upper, margin = 0):
  blanks = " " * margin
  print(blanks, lower, upper)
  if lower > upper:
    print(blanks, 0)
    return 0
  else:
    result = ourSum(lower+1, upper, margin+4)
    print(blanks, result)
    return result

ourSum(1,4)
 1 4
     2 4
         3 4
             4 4
                 5 4
                 0
             4
         7
     9
 10
10

可以清晰看到递归函数的运行过程