Typescript's template literal types are awesome when creating values that have to match a specific format. But depending on the format it can sometimes be tric

Typescript's template literal types are awesome when creating values that have to match a specific format. But depending on the format it can sometimes be tricky to narrow a string back down to that format. We have type guards to do that narrowing. (see: https://www.typescriptlang.org/docs/handbook/2/narrowing.html#using-type-predicates https://www.typescriptlang.org/docs/handbook/2/narrowing.htm..., but their older example is a little easier to read: https://www.typescriptlang.org/docs/handbook/advanced-types.html#type-guards-and-differentiating-types https://www.typescriptlang.org/docs/handbook/advanced-types....) If writing the check is too tricky, sometimes it can just be easier to track the type of a value with the value (if you can be told the type externally) with tagged unions (AKA: Discriminated unions). See: https://www.typescriptlang.org/docs/handbook/typescript-in-5-minutes-func.html#discriminated-unions https://www.typescriptlang.org/docs/handbook/typescript-in-5... And if the formats themselves are generated at runtime and you can use the "unique" keyword to make sure different kinds of data are treated as separate (see: https://www.typescriptlang.org/docs/handbook/symbols.html#unique-symbol https://www.typescriptlang.org/docs/handbook/symbols.html#un...). You can combine `unique symbol` with tagged unions and type predicates to make it easier to tell them apart.