map length (tiers :: [[ IntSet ]])  =  [1,1,1,2,2,3,4,5,6,8,10,12,...]

length (list :: [ IntSet ])  =  Infinity

allUnique (list :: [ IntSet ])  =  True

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

tiers :: [IntSet]  =
  [ [fromList []]
  , [fromList [0]]
  , [fromList [1]]
  , [ fromList [0,1]
    , fromList [-1]
    ]
  , [ fromList [-1,0]
    , fromList [2]
    ]
  , [ fromList [0,2]
    , fromList [-1,1]
    , fromList [-2]
    ]
  , [ fromList [-1,0,1]
    , fromList [-2,0]
    , fromList [1,2]
    , fromList [3]
    ]
  , [ fromList [0,1,2]
    , fromList [0,3]
    , fromList [-2,1]
    , fromList [-1,2]
    , fromList [-3]
    ]
  , [ fromList [-2,0,1]
    , fromList [-1,0,2]
    , fromList [-3,0]
    , fromList [1,3]
    , fromList [-2,-1]
    , fromList [4]
    ]
  , [ fromList [0,1,3]
    , fromList [-2,-1,0]
    , fromList [0,4]
    , fromList [-1,1,2]
    , fromList [-3,1]
    , fromList [-1,3]
    , fromList [-2,2]
    , fromList [-4]
    ]
  , [ fromList [-1,0,1,2]
    , fromList [-3,0,1]
    , fromList [-1,0,3]
    , fromList [-2,0,2]
    , fromList [-4,0]
    , fromList [-2,-1,1]
    , fromList [1,4]
    , fromList [-3,-1]
    , fromList [2,3]
    , fromList [5]
    ]
  , [ fromList [-2,-1,0,1]
    , fromList [0,1,4]
    , fromList [-3,-1,0]
    , fromList [0,2,3]
    , fromList [0,5]
    , fromList [-1,1,3]
    , fromList [-2,1,2]
    , fromList [-4,1]
    , fromList [-1,4]
    , fromList [-3,2]
    , fromList [-2,3]
    , fromList [-5]
    ]
  , ...
  ]