Ah...let me back up. So the dataset going into the function is currently a

PartitionedDataSet

, which we setup this way because it would allow us to load the information that we need from the directory. There are checks that are performed to ensure that the file is the right one (checking filename, etc). At the end, after all the processing, the function takes each

DataFrame

and adds it to a list which is then concatenated into a single

DataFrame

.