join +quickcheck

joinRose :: Rose (Rose a) -> Rose a
QuickCheck Test.QuickCheck.Property
conjoin :: Testable prop => [prop] -> Property
QuickCheck Test.QuickCheck.Property, QuickCheck Test.QuickCheck
Take the conjunction of several properties.
disjoin :: Testable prop => [prop] -> Property
QuickCheck Test.QuickCheck.Property, QuickCheck Test.QuickCheck
Take the disjunction of several properties.