Generating Fibnocci series

		
class fibnum:
    
    def __init__(self):
        self.fn2 = 1 # 
        self.fn1 = 1 # 
    
    def next(self): 
        # next() is the heart of any iterator
        # note the use of the following tuple to not only save lines of
        # code but also to insure that only the old values of self.fn1 and
        # self.fn2 are used in assigning the new values
        (self.fn1,self.fn2,oldfn2) = (self.fn1+self.fn2,self.fn1,self.fn2)
        return oldfn2
 
    def __iter__(self):
        return self


def main():
    f = fibnum()
    
    for i in f:
        print i
        if i > 20: break

if __name__ == "__main__":
    main()