斐波那契数列（迭代器）

class Fibs:  def __init__(self):    self.a = 0    self.b = 1  def next(self):    self.a,self.b = self.b , self.a+self.b    return self.a  def __iter__(self):    return selffibs = Fibs()for f in fibs:  if f < 100:    print f  else:    break