map length (tiers :: [[ Nat4 ]])  =  [1,1,1,1]

length (list :: [ Nat4 ])  =  4

allUnique (list :: [ Nat4 ])  =  True

ratioRepetitions (list :: [ Nat4 ])  =  0 % 1

tiers :: [Nat4]  =
  [ [0]
  , [1]
  , [2]
  , [3]
  ]
