Power Query - Loop through unknown number of Tables and append them all - solved

This is a very simplified version of this thread. We have an Input Table that looks like:

where each Group of colored columns needs to be transformed in a separate Table (so 3 in this case) and at the end we want the 3 Tables to be Appended (Combined according to Power Query M language)

Challenge

The number of Groups may vary (i.e. from 1 to say 10) from time to time. So we need a query that is flexible enough to handle this variation

Note

In the above example the 1st Group has 3 columns, the 2nd has 4 and the last has 5. To properly Append/Combine Tables they all must have the same number of columns. That aspect of the problem is not detailed in the below Power Query M snipet.

How To

Power Quey M language doesn't offer an easy way to loop. This example uses the List.Generate function to do that the appropriate number of times to build each Table and then Append/Combine them

let

    ...

    GroupsList = Record.ToList(Table.FirstN(Source, 1){0}),

    NbGroups = List.Count(List.Distinct(GroupsList)),

    // Loop (actually NbGroups of times) to create a Table for each "Group"

    // At the end we get a List that contains Table(s)

    The next Step will Append/Combine all Table(s)

    TablesToAppend = List.Generate(

         ()=> [i = -1, j = 0, OutputTable = #table({"Col","Index","Index2"},{})],

            each [i] < NbGroups,

                each

                    [

                        j = [j] +1,

                        ...,              // step1 to build the OutputTable

                        ...,              // step2 to build the OutputTable

                        TableIdx = ...,   // step3 to build the OutputTable

                        OutputTable = Table.AddIndexColumn(TableIdx, "Index2", j, 1),

                        i = [i] +1

                    ],

                each [OutputTable]

                                  ),

    // Append all tables from above List

    TablesAppended = Table.Combine(List.Transform(TablesToAppend, each (_))),

    ...

in

    ...