prop_geoGrade x y = 
  grade geoProd == grade x + grade y - 2*common
    where common = popCount $ x .&. y
          _ :* geoProd = x `geo` y
prop_geoGrade x y = 
  grade geoProd == grade x + grade y - 2*common
    where common = popCount $ x .&. y
          _ :* geoProd = x `geo` y
prop_geoGrade x y = 
  grade geoProd == grade x + grade y - 2*common
    where common = popCount $ x .&. y
          _ :* geoProd = x `geo` y