Sample the neighbour value from a list

Let say, I have a list:

[Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec]

and I randomly choose the index (let say idx=4, thus "May"), I want my function to return

[Mar,Apr,May,Jun,Jul]

If the index is 0 (Jan) or 1 (Feb) then I want my function to return [Jan,Feb,Mar,Apr,May]. The length of returned list is always 5.

How to create such function in Python3?

Simple question but why my head starts to explode?

Thanks.