Mixing the freds at different multiple boundaries within the same string is a very neat way of testing.
I can't take credit for that, it was copied from johngg's answer. I just made it a little more readable.

In reply to Re^3: A regex that only matches at offset that are multiples of a given N? by smls
in thread A regex that only matches at offset that are multiples of a given N? by BrowserUk

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