input: def fibonacci(n: int) -> None:
      """ Print Fibonacci series up to a given number n.
      >>> fibonacci(5)
      0
      1
      1
      2
      3
      >>> fibonacci(10)
      0
      1
      1
      2
      3
      5
      8
      13
      21
      34
      """
      a, b = 0, 1
      if n < 0: 
          print("Incorrect input") 
      else:
          while a <= n:
              print(a)
              a, b = b, a + b
output:     a, b = 0, 1
      if n < 0: 
          print("Incorrect input") 
      else:
          while a <= n:
              print(a)
              a, b = b, a + b