Here’s the quick overview:
1. In the Power Query editor in Power BI Desktop, choose “Column from Examples” from the “Add Column” tab.
2. Enter the values that the new column should have for rows that are already in your data set.
3. Review the values that Power Query is suggesting for the other rows, and when they are all correct, choose OK, and then say “Ooooooohhhhh” when Power Query does all the work for you.
It’s a little hard to see from Matthew’s image but this is a great feature when you have a regular pattern but don’t want to put together a regular expression yourself.