map length (tiers :: [[ Set Nat2 ]])  =  [1,1,1,1]

length (list :: [ Set Nat2 ])  =  4

allUnique (list :: [ Set Nat2 ])  =  True

ratioRepetitions (list :: [ Set Nat2 ])  =  0 % 1

tiers :: [Set Nat2]  =
  [ [Set []]
  , [Set [0]]
  , [Set [1]]
  , [Set [0,1]]
  ]