Image results: python for loop index

Wikipedia results

1.Iterator

iterable (but not necessarily indexable) object. Several languages, such as Perl and Python, implement streams as iterators. In Python, iterators are objects

https://en.wikipedia.org/wiki/Iterator

2.Generator (computer programming)

the right way. For example, a ranged loop like for x = 1 to 10 can be implemented as iteration through a generator, as in Python‘s for x in range(1, 10)

https://en.wikipedia.org/wiki/Generator (computer programming)