> Shouldn’t the collection of rows be a set or list, not a dictionary? I didn't mention the collection of rows, I mentioned the rows themselves. > The “rows t

> Shouldn’t the collection of rows be a set or list, not a dictionary? I didn't mention the collection of rows, I mentioned the rows themselves. > The “rows themself” being an ordered map means you are referring to the columns No, it means I'm referring to the rows themselves. The rows themselves are each ordered mappings. Hope this helps to clarify things. Happy to keep repeating this as many times as necessary.