Fix Python – What is the recommended way to use Vim folding for Python code

I am interested in enabling code folding in Vim for Python code. I have noticed multiple ways to do so.
Does anyone have a preferred way to do Python code folding in Vim? I.e,

Do you have a particular Vim plugin that you use and like?
Do you use manual folding or do you place markers in comments?
Any other recommended ways to do code folding for….

Fix Python – Running Python code in Vim

I am writing Python code using Vim, and every time I want to run my code, I type this inside Vim:
:w !python

This gets frustrating, so I was looking for a quicker method to run Python code inside Vim. Executing Python scripts from a terminal maybe?
I am using Linux.

Fix Python – How to comment out a block of Python code in Vim

I was wondering if there was any key mapping in Vim to allow me to indent certain lines of code (whether those lines have been selected in visual mode, or n lines above/below current cursor position).
So basically something that converts the following
def my_fun(x, y):
return x + y

#def my_fun(x, y):
# return x + y

I am okay with usin….