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