Append first item to end of iterable in Python

Question

I need to append the first item of a (general) iterable as the final item of that iterable (thus "closing the loop"). I've come up with the following:

from collections.abc import Iterable
from itertools import chain

def close_loop(iterable: Iterable) -> Iterable:
    iterator = iter(iterable)
    first = next(iterator)
    return chain([first], iterator, [first])

# Examples:
list(close_loop(range(5)))  # [0, 1, 2, 3, 4, 0]
''.join(close_loop('abc'))  # 'abca'

Which works, but seems a bit "clumsy". I was wondering if there's a more straightforward approach using the magic of itertools. Solutions using more_itertools are also highly welcome.

Answer 1

Here is a version which doesn't use itertools

def close_loop(iterable):
    iterator = iter(iterable)
    first = next(iterator)
    yield first
    yield from iterator
    yield first