member x (Bin _s a l r) = case x `compare` a of
  LT -> member x l
  GT -> member x r
  EQ -> True
member x (Bin _s a l r) = case x `compare` a of
  LT -> member x l
  GT -> member x r
  EQ -> True
member x (Bin _s a l r) = case x `compare` a of
  LT -> member x l
  GT -> member x r
  EQ -> True