def wrapper(func):
     def _inner(a):
         results = []
         results.append(func(a))
         v = results[0].next()
         idx = 0
         while True:
             if not isinstance(v, Result):
                 results.append(func(v))
                 idx = len(results) - 1
                 v = results[idx].next()
             else:
                 del results[idx]
                 if len(results) == 0: break
                 else:
                     idx -= 1
                     v = results[idx].send(v.v)
         return v.v
     return _inner
 
 @wrapper
 def fact(a):
     if a == 1:
         yield Result(1)
     yield Result(a * (yield a-1))
 
 @wrapper
 def count(a):
     if a == []: yield Result(0)
     else:
         yield Result(1 + (yield a[1:]))
 
 @wrapper
 def fib(a):
     if a in [1,2]: yield Result(1)
     else:
         z = (yield a-1)
         b = (yield a-2)
         yield Result( z + b )
 
 @wrapper
 def fib(a):
     if a in [1,2]: yield Result(1)
     else:
         z = (yield a-1)
         b = (yield a-2)
         yield Result( z + b )
 
 
 @wrapper
 def reverse(lis):
     if lis == []: yield Result([])
     else:

         yield Result( [(yield lis[1:]), lis[0]] )