Because there are two print statements. First is inside function and second is outside function. When a function doesn't return anything, it implicitly returns None.

Use return statement at end of function to return value.

e.g.:

Return None.

>>> def test1():
...    print "In function."
... 
>>> a = test1()
In function.
>>> print a
None
>>> 
>>> print test1()
In function.
None
>>>
>>> test1()
In function.
>>> 

Use return statement

>>> def test():
...   return "ACV"
... 
>>> print test()
ACV
>>> 
>>> a = test()
>>> print a
ACV
>>>