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# [APL(Dyalog Unicode)][1], <sup><s></s></sup>4 bytes <sup>[SBCS][2]</sup>
Anonymous tacit prefix function.
```
,∘≢⌸
```
[Try it on APLgolf!](https://razetime.github.io/APLgolf/?h=AwA&c=03nUMeNR56JHPTsA&f=e9Q39VHbhDQFQyA0UjBWMFUwUzDjegQWVdfV1VWHstMUHvWuwSpuCNRhDtYN1AmkTY0VTBQMDRQA&i=AwA&r=tio&l=apl-dyalog&m=train&n=f)

[1]: https://dyalog.com
[2]: https://github.com/abrudz/SBCS

…`⌸` between each unique element and its indices, apply:

`,∘≢` concatenate the unique element to the tally of indices