called a symmetric numeral systems so this is an alternative to arithmetic coding as Peter was saying and it's especially appealing because it it's well first of all it's very simple and you can implement it on on you can implement it in a very efficient way which makes it actually practically usable and it also has some nice stack like properties that make it compatible with bits black coding so I'll just first take some time to describe what ENS actually is so again ans which is something like just like you're a thematic coding is a way of