text: fib_func = (lambda f: lambda n: f(f, n))(
      lambda f, n: None if n < 0 else (0 if n == 0 else (1 if n == 1 else f(f, n - 1) + f(f, n - 2))))
  [fib_func(i) for i in range(-2, 10)]
  [None, None, 0, 1, 1, 2, 3, 5, 8, 13, 21, 34]
  