new_contents: #!/usr/bin/env python3
  
  def fibs():
      fib1, fib2 = 1, 1
      while True:
          yield fib1
          fib1, fib2 = fib2, fib1 + fib2
  
  print(next(i for (i, f) in enumerate(fibs(), 1) if len(str(f)) == 1000))
  
subject: Solve problem 25