>>> i=iter('ABC')
>>> i.next()
--> 'A'
>>> i.next()
--> 'B'
>>> i.next()
--> 'C'
>>> i.next()
---------------------------------------------------------------------------
StopIteration                             Traceback (most recent call last)
<ipython-input-75-e590fe0d22f8> in <module>()
----> 1 i.next()

StopIteration: 
