def get_sum(a,b):
if a == b:
return a
elif a < b:
return sum(range(a, b + 1))
else:
return sum(range(b, a + 1))
def get_sum(a,b):
return sum(xrange(min(a,b), max(a,b)+1))
原文：http://www.cnblogs.com/dreamyu/p/7602574.html