Adding flush=True for print()

Based on:

#+BEGIN_QUOTE
From: cs.wzpan@gmail.com
Suggestion: Hello Swaroop,

Nice tutorial on Python! Definitely be my introduction to Python.

One comment though: in the [Python : Exceptions]
(http://swaroopch.com/notes/python_en-exceptions/) session I think
you'd better modify one line in the finally.py from "print(line,
end='')" to "print(line, end='', flush=True)" to make sure that the
screen will output something every 2 seconds. Otherwise in my machine
I cannot see the output before I press my keyboard or the counting
loop ends.
#+END_QUOTE
Removing usage of __del__ destructor

To avoid confusions such as http://stackoverflow.com/q/1935153/4869
Changing examples to make numbers clearer

Based on:

   ---------- Forwarded message ----------
   From: Horst JENS <horstjens@gmail.com>
   Date: Tue, Aug 28, 2012 at 3:02 PM
   Subject: suggestion for "byte of python 3.x" Operators and their usage
   To: swaroop@swaroopch.com

   Dear Swaroop,

   sadly your famous "byte of python wiki" does not re-sent me my
   password for the byte-of-python3.x wiki ( Username HorstJENS ).
   Probably beacause i changed my email adress.

   So i write you directly:

   This is a suggestion for the page:
   http://www.swaroopch.org/notes/Python_en:Operators_and_Expressions

   You wrote in the table explaining the math operators of python 3.x:

   /      Divide               Divide x by y
   4 / 3 gives 1.3333333333333333.
   //     Floor Division   Returns the floor of the quotient
   4 // 3 gives 1.
   %   Modulo              Returns the remainder of the division    8 % 3
   gives 2. -25.5 % 2.25 gives 1.5.

   While working on this page with a student ( 13, german speaker) i
   noticed that both the divide and the floor division operation return
   the result 1 in your examples. ( we also tested 4 %3 , also
   returning 1) This is not ideal as it makes it less clear what the
   floor division and what the modulo is.

   I suggest to use instead those examples:

   /  Divide               Divide x by y
  10 / 3 gives 3.3333333333333333.
   // Floor Division   Returns the floor of the quotient             10
   // 3 gives 3.
   % Modulo            Returns the remainder of the division    10%3 gives 1

   greetings,
  -Horst