py4e book exercise not working when compiled

[adriand]

thanks!
this is why it's confusing and I'd like to understand why the different results before I move on with the course.
this is what I get

Python 3.5.3 (default, Jan 19 2017, 14:11:04) 
[GCC 6.3.0 20170118] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> data = 'From [email protected] Sat Jan  5 09:14:16 2008'
>>> atpos = data.find('@') 
>>> print (atpos)
21
>>> spos = data.find(' ',atpos) 
>>> print (spos)
-1
>>> host = data[atpos+1 : spos]
>>> print (host)
uct.ac.za Sat Jan  5 09:14:16 200
>>>