Automatic formatting of code in VIM

In Vim there is also the operation of the automatic formatting code, like the CTRL + Shift +f in Eclipse, which, although very powerful, usually destroys the original indentation of the Code,

So it's not recommended to use in a language such as Python for indenting instead of parentheses and in code that has been indented by the source program, so let's say the following steps:

1,gg jump to the first line

2,shift+v go to Visual mode

3,shift+g Select All

4, press the Magic =

You will be surprised to find that the code automatically indented, hehe, of course, may also be a tragedy.