Have you ever needed to ingest a number of same-structured inputs into your Power BI report and repeat the refresh periodically? If so, then it seems like a perfect use-case for automation using custom-made Power Query functions. You might have already tried authoring such a function, as Power Query is often able to generate the whole thing automatically, in a user-friendly way.  But what do you do if you need to handle a more complex scenario, include multiple inputs as arguments of the function or something has just stopped working and you're unsure how to fix it? During this session you will learn the Power Query custom functions from A to Z. I will first show you how to identify a good use-case for this feature. Further into the session, you will learn how to create such functions from scratch as well as what are their semantics and components. I will explain how to effectively work with custom functions and debug them over a number of use-cases. You will also learn a number of common pitfalls and bad practices to avoid. After this session you will be able to: - recognize use-cases for automation using Power Query custom functions. - create custom functions to handle complex scenarios. - debug and optimize custom functions. It would be great if prior to this session you have some experience working with Power Query and basic transformations within it.