How do we feel about using [`enum`](https://docs.python.org/3.8/library/enum.html) for [site type](https://github.com/DOI-USGS/dataretrieval-python/blob/87351a13b7c7c1cf035e9a359addf289d14f5e50/dataretrieval/nwis.py#L609-L613), [county code](https://github.com/DOI-USGS/dataretrieval-python/blob/87351a13b7c7c1cf035e9a359addf289d14f5e50/dataretrieval/nwis.py#L583-L586C15), etc., instead of `str`? It would fit nicely with: - #97
How do we feel about using
enumfor site type, county code, etc., instead ofstr?It would fit nicely with: