Random contiguous slice of list in Python based on a single random integer

Using a single random number and a list, how would you return a random slice of that list?

For example, given the list [0,1,2] there are seven possibilities of random contiguous slices:

1. [ ]


2. [ 0 ]


3. [ 0, 1 ]


4. [ 0, 1, 2 ]


5. [ 1 ]


6. [ 1, 2]


7. [ 2 ]

Rather than getting a random starting index and a random end index, there must be a way to generate a single random number and use that one value to figure out both starting index and end/length.