let
Source = "",
//Each line basically stands on it's own, rather than building on the previous line, to visually show how it all fits as you step through
ListRepeatA = List.Repeat({"A"}, 7),
ListZipA = List.Zip({List.Repeat({"A"}, 7), {"1".."7"}}),
//This first combine maintains state
ListCombineA = List.Combine({{}, List.Zip({List.Repeat({"A"}, 7), {"1".."7"}})}),
ListRepeatB = List.Repeat({"B"}, 7),
ListZipB = List.Zip({List.Repeat({"B"}, 7), {"1".."7"}}),
// Technically the empty {} list contains the ListZipA info to maintain state
ListCombineB = List.Combine({{}, List.Zip({List.Repeat({"B"}, 7), {"1".."7"}})}),
ListRepeatC = List.Repeat({"C"}, 7),
ListZipC = List.Zip({List.Repeat({"C"}, 7), {"1".."7"}}),
// Technically the empty {} list contains the ListZipA & ListZipB info to maintain state
ListCombineC = List.Combine({{}, List.Zip({List.Repeat({"C"}, 7), {"1".."7"}})}),
// I use List.Union to simulate what the List.Accumulate() function returns. In truth, it returns ListCombineC as it holds all the lists.
ListAccumulate = List.Union({ListCombineA,ListCombineB,ListCombineC}),
//Text combine each list
ListTransform = List.Transform(ListAccumulate, each Text.Combine(_))
in
ListTransform