type alias Pairimport { type Pair } from "https://deno.land/x/cc_types@v1.0.0-beta.13/mod.ts"; Make currency pair with no duplicate Type ParametersQ extends stringB extends stringoptionalSeparator extends string = "_"optional_ = Qdefinition: B extends _ ? Pair<Exclude<Q, B>, B, Separator> : Join<Q, B, Separator>