[docs] [issue21739] Add hint about expression in list comprehensions (https://docs.python.org/2/tutorial/datastructures.html#list-comprehensions)

R. David Murray added the comment: The only demure I got on this was from Ezio, who objected that the concept of 'scope' hadn't been introduced yet in the tutorial. So I reworded it to avoid the word 'scope'. Thanks, Rose. ---------- resolution: -> fixed stage: commit review -> resolved status: open -> closed _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue21739> _______________________________________