1、end keyword , Let the output data be on one line and specify the punctuation mark followed by the data
print(b,end=",")
2、sep： The separator between strings 
3、 Recursive functions trade space for time , Each calculation will create a function stack , If it's too deep , Can cause data overflow
Reference to write a recursion 
I really don't understand why n=6 When , The results of 13 ah （ I'm a programming dog ）, Do you have a partner to explain
4、 It seems to write a dead cycle , Then appear ”Code is already running!“ The error of
terms of settlement ：A、 Output —— Right click ——stop code run
B、 No, stop code run What do I do ？ctrl+alt+m See if there's any
C、 There is still nothing to do ？ stay ”Code is already running!“ Error reporting of , Click Manage extensions , take code Runner Ban , And then it's all right
