prop_invertVersionRange :: VersionRange -> Version -> Bool
prop_invertVersionRange vr v' =
     withinRange v' (invertVersionRange vr)
  == not (withinRange v' vr)
prop_invertVersionRange :: VersionRange -> Version -> Bool
prop_invertVersionRange vr v' =
     withinRange v' (invertVersionRange vr)
  == not (withinRange v' vr)
prop_invertVersionRange vr v' =
     withinRange v' (invertVersionRange vr)
  == not (withinRange v' vr)