into: test foo <- CSV

Does the concern only exist when there is preexisting data in the target data descriptor?  Perhaps we should have some sort of `drop` capability?  I've used this as-is in the following two contexts:

1.  I've just created a new, empty data descriptor and want to put data into it.  In this situation both meanings are equivalent.
2.  I actually want to put many CSV files into one SQL database so I call `into` repeatedly