mathlib

8919541a - feat(data/finset): new basic material on finsets and fintypes (#2068)

feat(data/finset): new basic material on finsets and fintypes (#2068) * feat(data/finset): additional basic material * minor fixes * golfed * Update src/data/finset.lean Co-Authored-By: Johan Commelin <johan@commelin.net> * Update src/data/finset.lean Co-Authored-By: Johan Commelin <johan@commelin.net> * Update src/data/finset.lean Co-Authored-By: Johan Commelin <johan@commelin.net> * golfed Co-authored-by: Johan Commelin <johan@commelin.net> Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>