Excel PowerQuery: how do I add an IsNotNull column

I have a simple function that I’d like to run on the values in a column, resulting in another column.

    let 
        ThisIsNotNull = (input) => if (input = null) then false else true,
        Source = ...

eventually there is a text column with Nulls in it, let’s call it TextColumn.
I’d like to add another column alongside it with a value of =ThisIsNotNull(TextColumn).

>Solution :

Add column… Custom column with formula

 = ThisIsNotNull([NameOfColumnToTest])

But really you can skip the function and just use

 = if [NameOfColumnToTest] = null then false else true