I want to separate another set of numbers with a dot (period), how can I do it, since I can either define it as $"=':' or $"='.'

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Well, not strictly, since due to the way $" is actually used, with some trickery you can tie it to some suitable class. One such example I could find on PM is Re: Surprised by join, but I'm quite sure it has come out in other occasions as well.
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