1 class FloatRange:
 2     def __init__(self,start,end,step = 0.1):
 3         self.start = start
 4         self.end = end
 5         self.step = step
 6     
 7     def __iter__(self):
 8         t = self.start
 9         while t <= self.end:
10             yield t
11             t += self.step
12     
13     def __reversed__(self):
14         t = self.end
15         while t >= self.start:
16             yield t
17             t -= self.step
18             
19 if __name__ == "__main__":
20     
21     for x in FloatRange(1.0,4.0,0.5):
22         print x
23     
24     for x in reversed(FloatRange(1.0,4.0,0.5)):
25         print x
26