Templates don't even have to be processed into a string. The article shows an example where the Template is processed into an HTML mini-DOM. It's maybe not obvi

Templates don't even have to be processed into a string. The article shows an example where the Template is processed into an HTML mini-DOM. It's maybe not obvious because the DOM object is immediately stringified to show sample output, but you could imagine manipulating the DOM object in a few more steps before stringifying it, or maybe you are running in WASM in a browser and using that mini-DOM directly as a Virtual DOM passed to JS to work with. Also, in addition to the other SQL example using "?" to fill in the "holes" for parameters in an SQL friendly way, some DBs also support named parameters, so the "hole" in the string form might be naively replaced with something like `f"@{item.expression}"` and that also forms the key in a dict to pass as parameters. (You'd want to make sure that the expression inside the template is useful as a parameter name, and not something more exotic like {1 + 3} or {thing for thing in some_list}, in which cases you are probably auto-assigning some other parameter name.)