Because there are two print statements. First is inside function and second is outside function. When function not return any thing that time it return None value.
Use return
statement at end of function to return value.
e.g.:
Return None value.
>>> 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
>>>