process.dedupe() using sets instead of lists & dict.keys()

[UpwardTrajectory]

Maybe no one asked for this, but I saw a very minor improvement. (This is my first ever contribution attempt to a stranger's library, I'm open to critiques re: my process.)

This is slightly more readable and doesn't use dict.keys() in order to get set functionality. Previously,

deduped = process.dedupe(contains_dupes)
type(deduped)

dict_keys

but now type(deduped) = list