https://issues.dlang.org/show_bug.cgi?id=23250

          Issue ID: 23250
           Summary: Unicode regional indicators are not paired correctly
           Product: D
           Version: D2
          Hardware: x86_64
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: phobos
          Assignee: nobody@puremagic.com
          Reporter: Ajieskola@gmail.com

If there are many flags side-by-side, they should count as a grapheme each. But
regional indicators do not currently get paired like that. Due to that,
"🇬🇧🇭🇰🇸🇬🇯🇪🇰🇾".byGrapheme.walkLength returns 1 when it should return 5.

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