function ModeN(const A: array of Integer): TArray<Integer>;
begin
 if Length(A) = 0 then
 raise EArgumentException.Create('Array is empty');
 var MaxCount: Cardinal := 0;
 var Counts := TDictionary<Integer,Cardinal>.Create;
 try
 for var X in A do
 begin
 var C: Cardinal;
 if not Counts.TryGetValue(X, C) then
 C := 0;
 Inc(C);
 Counts.AddOrSetValue(X, C);
 if MaxCount < C then
 MaxCount := C;
 end;
 // equivalent test?: if MaxCount = 1 then
 if Length(A) = Counts.Count then 
 begin
 // All numbers are unique => no mode
 SetLength(Result, 0);
 Exit;
 end;
 var Results := TList<Integer>.Create;
 try
 for KV in Counts do
 begin
 if KV.Value = MaxCount then
 Results.Add(KV.Key);
 end;
 Result := Results.ToArray;
 finally
 Results.Free;
 end;
 finally
 Counts.Free;
 end;
end;