Differences between VOC and CPython

StopIteration

A StopIteration is a signal raised by an iterator to tell whomever is iterating that there are no more items to be produced. This is used in for loops, generator functions, etc. The org.python.exception.StopIteration exception differs from the CPython StopIteration exception in that it is a singleton. This was introduced in `PR #811<https://github.com/beeware/voc/pull/881>`_ as part of a performance effort as it yields a non-trivial performance improvement for nested for loops. However, it also means that an equality comparison between two StopIteration exceptions will always be True, which is not the case in CPython.