fn Encoding::decode(self : Encoding, tokens : ArrayView[Int]) -> String raise DecodingError

fn Encoding::encode(self : Encoding, piece : StringView) -> Array[Int] raise

fn Encoding::new(mergeable_ranks~ : Map[Bytes, Int], special_tokens~ : Map[String, Int], pat_str~ : String) -> Encoding raise

fn Encoding::special_tokens(self : Encoding, piece : String) -> Int?