Matt Allington solves a problem in Power Query:
Suppose you have data in the form of dates (not consecutive) with a value for each of the dates (see the table below left side). You need to expand the rows of the table (create the missing rows) so that you will have all the consecutive dates in the given range and each of the dates has the previous updated value (see the table below right side).
The solution has a pretty large number of steps but is straightforward.