Iteration Flow and StopIteration

Iteration begins when Python calls iter() on an iterable.

This returns an iterator object.

Python then repeatedly calls __next__() on the iterator to fetch values.

This process continues until the iterator signals completion.

StopIteration is a special exception used by iterators to indicate that no more values are available.

It is raised inside the __next__() method.

The second call raises StopIteration because the iterator is exhausted.

When using a for loop, Python automatically handles the StopIteration exception.

Internally, the loop stops gracefully when StopIteration is raised.

The exception is not shown to the user.

This behavior ensures clean and predictable looping.