behavior of `workflow --clean data/corpus.csv`?

The big thing we need to decide here is how this should behave? Should it *only* remove `data/corpus.csv` or should it remove `data/corpus.csv` and all its dependencies? 

To me, it seems more natural to only remove `data/corpus.csv` but perhaps others have a different intuitive sense of what it should do. I guess it depends on how this is used in practice so I'll wait for feedback before making any decisions on this...