Python 3.7.0 (v3.7.0:1bf9cc5093, Jun 26 2018, 23:26:24) 
[Clang 6.0 (clang-600.0.57)] on darwin
Type "copyright", "credits" or "license()" for more information.
>>> 
========== RESTART: /Users/koc/Desktop/myfun.py ==========
>>> abc(3,4)
25
>>> 
========== RESTART: /Users/koc/Desktop/myfun.py ==========
>>> abc(3,4)
25
>>> new(3,4)
25
>>> 2 + abc(3,4)
27
>>> 2 + new(3,4)
25
Traceback (most recent call last):
  File "<pyshell#4>", line 1, in <module>
    2 + new(3,4)
TypeError: unsupported operand type(s) for +: 'int' and 'NoneType'
>>> x = abc(3,4)
>>> x
25
>>> y = new(3,4)
25
>>> y
>>> abc(3,4)
25
>>> new(3,4)
25
>>>