python的range（）函数

The range function has three different versions:

1. range(stop)
2. range(start, stop)
3. range(start, stop, step)

4. range(6) # => [0,1,2,3,4,5]range(1,6) # => [1,2,3,4,5]range(1,6,3) # => [1,4]