[fireflies_]

Your code is doing something pretty different from the examples above. You're just calculating the nth fibonacci number, not creating an infinite fibonacci _sequence_. Eliding the explicit recursive structure is the point of the exercise!

Admittedly Python's facilities for doing that with some mutable state are pretty nice:

  from itertools import islice

  def fib():
      a, b = 0, 1
      while True:
          yield a
          a, b = b, a + b

  list(islice(fib(), 10)) == [0, 1, 1, 2, 3, 5, 8, 13, 21, 34]

[andrewprock]

I wasn't speaking to the goal of generating a sequence that can be lazily evaluated.

I was speaking to readability.