Count of how many times a unique value appears across all columns and rows of a dataset?

I have unique IDs in rows where columns are the IDs of their 'sent' friends. To get a count of 'received' friends, I need to get a count for how many times an ID appears across all columns and rows of the dataset. This is easy in R, but I'd like to stay with Stata for this project.

Toy data above. Here, there are four mentions of ID #1, three mentions of ID #4, etc.

I want to generate a variable containing the count of how many times each ID value in the first column is mentioned in any column of the data set. This is illustrated in the ID_mentions column.

Turns out I wrote something in this territory. You would need to install this with ssc install tab_chi

* Example generated by -dataex-. For more info, type help dataex
clear
input byte(id f1_id f2_id f3_id)
1 2 3 4
2 4 1 .
3 1 2 .
4 2 1 3
end

tabm *id

           |                   values
  variable |         1          2          3          4 |     Total
-----------+--------------------------------------------+----------
        ID |         1          1          1          1 |         4 
     F1_ID |         1          2          0          1 |         4 
     F2_ID |         2          1          1          0 |         4 
     F3_ID |         0          0          1          1 |         2 
-----------+--------------------------------------------+----------
     Total |         4          4          3          3 |        14 

EDIT To count all mentions:

gen mentions = . 

quietly forval i = 1/`=_N' { 
    egen work = anycount(*id), value(`=id[`i']')
    su work, meanonly 
    replace mentions = r(sum) in `i'
    drop work 
}

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