example suggestion: Avoiding splitting a Str into characters

[Anton-4]

From the Roc Str reference:

If it seems like a good idea to split a string into "characters" (graphemes), you should definitely stop and reconsider whether this is really the best design. Almost always, doing this is some combination of more error-prone or slower (usually both) than doing something else that does not require taking graphemes into consideration.

It would be good to have several snippets that demonstrate this.