[python] self-study notes

1. Environment installation

　　1.1 python working environment 2.7.14

　　1.2 pycharm community2018.1.1 4 x64

2. The first line of code

　　2.1 python interactive mode,

　　　　 >>>10+20

　　　　30

　　　　exit() to exit interactive mode.

　　2.2 Run the .py file Enter in command line mode (the folder where the .py file is located)

　　　　python test.py

　　The Python interactive environment automatically prints the result of each line of Python code, but running Python code directly does not.