Add element to list in a list of list

[JW_van_Holst]

I want to add 4 to the list {5,6} and keep the others elements (lists) of the (outer) list

Source = {{1,2,3}, {5,6}, {12,13}}

//JW

[AlB · Accepted solution]

Hi @JW_van_Holst 

Place the following M code in a blank query to see the steps.

let
Source = {{1,2,3}, {5,6}, {12,13}},
res_ = List.Transform(Source, each if _ = {5,6} then _ & {4} else _)
in
res_

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