checking for last item in for loop

[Gribouillis]

You could use itertools

>>> import itertools as itt
>>> L = list('ulivohta')
>>> imode = itt.chain(itt.repeat('rb', len(L)-1), ('r',))
>>> 
>>> for item, mode in zip(L, imode):
...     print(item, mode)
... 
u rb
l rb
i rb
v rb
o rb
h rb
t rb
a r
>>>