code: def fibo(max_value=None):
      
      a = 1
      b = 1
      while True:
          if max_value is None or a < max_value:
              yield a
              a, b = b, a + b
          else:
              yield max_value
docs: Generator for fibonaccial decay.
  
      Args:
          max_value: The maximum value to yield. Once the value in the
               true fibonacci sequence exceeds this, the value
               of max_value will forever after be yielded.