quetion about "+=" and "runtime"

[Terry Reedy]

<gagaguy at gmail.com> wrote in message 
news:1123123359.768132.112990 at g47g2000cwa.googlegroups.com...
> 1.i saw "+=" in a program code,but i haven't see it before,neither can
> i find it in a cook,who can tell me the usage of "python0"

It probably is in the tutorial and certainly is in the reference manual.
I don't understand "usage of 'python0'".

> 2.how can i know how long does a program run?

time module

tjr