I normally would use a generator function. Each time you use a yield statement, it will add an item to the sequence.
The following will create an iterator that yields five, and then every item in some_list.
def __iter__(self):
yield 5
yield from some_list
Pre-3.3, yield from
didn’t exist, so you would have to do:
def __iter__(self):
yield 5
for x in some_list:
yield x