在汉诺塔递归的学习中我发现一个问题就是程序是如何实现c-->a或c-->b的呢
```python
Python 3.10.6 (tags/v3.10.6:9c7b4bd, Aug 1 2022, 21:53:49) [MSC v.1932 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
def move(n, a, b, c):
if not isinstance (n,(int or n <= 0 and n <-1)):
raise TypeError("'n' needs +int")
if n == 1:
... print(a, '-->', c)
... else :
... move(n-1, a, c, b)
... move(1, a, b, c)
... move(n-1, b, a, c)
...
>>> move(4,'A','B','C')
A --> B
A --> C
B --> C
A --> B
C --> A
C --> B
A --> B
A --> C
B --> C
B --> A
C --> A
B --> C
A --> B
A --> C
B --> C
```
递归实现，在else语句中你可以发现move函数传参时a,b,c的位置有所变化，这就可以实现c-->a和c-->b的移动