A generalisation of the MAP lambda helper function

This is a demonstration of the proposed MAP function used to solve a challenge provided by Oz_Sunray and Wyn Hopkins on data cleansing and vote counting.  The key element of my solution is to build a table of validated votes for each voter ID and each candidate (i.e. an array of arrays - much the same as any other problem of interest).  The formula is modularised using Lambda functions.  They are not that pretty, but neither are they impossible to follow.

"Worksheet formula"
= AggregateVotesλ(
      tblVOTES[VoterID],
      tblVOTES[[Vote1]:[Vote3]],
      weight,
      tblAvailable[AVAILABLE]
  )

which calls

/*  "FUNCTION NAME:  AggregateVotesλ"
    "DESCRIPTION:    Aggregates all votes to candidate colors" */
/*  "REVISIONS:      Date            Developer           Description"
    "                08 Sep 2024     Peter Bartholomew   Original Development"
*/
AggregateVotesλ
= LAMBDA(voterID, votesCast, weight, available,
     LET(
        person, TOROW(UNIQUE(voterID)),
        votes,  MAPλ(person, AssignVotesλ(voterID, votesCast, weight, available)),
        count,  HSTACK(available, BYROW(votes, SUM)),
        return, TAKE(SORT(count, 2, -1), 4),
        return
     )
  );

to build and aggregate the table of votes.  This, in turn, calls another Lambda function to clean and validate the votes corresponding to a single voterID

/*  "FUNCTION NAME:  AssignVotesλ"
    "DESCRIPTION:   Validates and assigns votes to candidate colors for a single voterID " */
/*  "REVISIONS:      Date            Developer           Description"
    "                08 Sep 2024     Peter Bartholomew   Original Development"
*/
AssignVotesλ
= LAMBDA(voterID, ballots, weight, available,
    LAMBDA(p,
        LET(
            // "In the case of duplicate ballots return first"
            votesCast, XLOOKUP(p, voterID, ballots),
            // "Remove invalid and repeated votes"
            valid,     COUNTIFS(available, votesCast),
            distinct,  EXPAND(UNIQUE(FILTER(votesCast, valid), TRUE), , 3, ""),
            // "Assign votes to candidate colours"
            assigned,  BYROW((distinct = available) * weight, SUM),
            assigned
        )
    )
);

I took the problem from Wyn's recording

https://www.youtube.com/watch?v=FIcxyLqzWcE