When Does iter() Called Internally

Iterators in Python are objects that implement both __iter__ and __next__ special methods. iter() is called internally to support:

• for loop.
• Tuple unpacking, example such as x, y = IterableObject
• Unpacking actual function parameters in function calls such as *args and **kwargs
• list, dict, & set comprehensions such as [e for e in L]
• Looping over text files line by line such as for line in file: print(line)
• Collection types construction such as list(obj) or tuple(obj)