type dispatching type conversion
eg: pounch
tree again, linked list a link list has a link list as its attribute value recursion - map, filter mutation - add
4道题目都是recursion,比较简单,但是需要脑子思考 Q4 partation
Q2 Q3 skip add 太简单了 tree recursion 多个recursion我记得
Q4 只能up right
Q5 好难好难
typeing test
x + y
- x
- y
- built in
repr repr ask its argument what is your repr method if not defined, default behavior #<main.A object at 0x0000020DF286E7B8>, not useful just a placeholder #A(),stupid shows more interesting info about A
tree yield - return
root depth 0