prop_unionVersionIntervals :: VersionIntervals -> VersionIntervals
                           -> Version -> Bool
prop_unionVersionIntervals is1 is2 v =
     withinIntervals v (unionVersionIntervals is1 is2)
  == (withinIntervals v is1 || withinIntervals v is2)
prop_unionVersionIntervals :: VersionIntervals -> VersionIntervals
                           -> Version -> Bool
prop_unionVersionIntervals is1 is2 v =
     withinIntervals v (unionVersionIntervals is1 is2)
  == (withinIntervals v is1 || withinIntervals v is2)
prop_unionVersionIntervals is1 is2 v =
     withinIntervals v (unionVersionIntervals is1 is2)
  == (withinIntervals v is1 || withinIntervals v is2)