Can I use namedtuple?
|          YES
|------------------------- Use namedtuple
|                          |Only two/three fields, forever?
|                          |---------------------------------- Consider tuples
|
|
|
|
|--Do I need order?
   |         YES
   |------------------------ Use list
   |
   |
   |
   |--- Can I have duplicates?
        |        YES
        |-------------------------------  Use Counter
        |
        |
        |
        |
        |-------------------------- Use set