def zip_with_next(xs: iter):
  a = next(xs)
  while True:
    try: b = next(xs)
    except StopIteration: break
    yield (a, b); a = b 

def generate_chain(initial_base, get_item, next_base):
  base = initial_base
  while True:
    try:
      yield get_item(base)
      base = next_base(base)
    except Exception: break

links = ("a", ("b", "c"))
flat_links = generate_chain(links, lambda t: t[0], lambda t: t[1])