hedgeUnion blo bhi Tip (Bin _ x l r) = join x (filterGt blo l) (filterLt bhi r)
hedgeUnion blo bhi Tip (Bin _ x l r) = join x (filterGt blo l) (filterLt bhi r)
hedgeUnion blo bhi Tip (Bin _ x l r) = join x (filterGt blo l) (filterLt bhi r)