refactor(library/data/rat/basic): cleanup proof
refactor(library/data/rat/basic): cleanup proof

Kha/lean,javra/lean,leanprover-community/lean,leanprover-community/lean,fgdorais/lean,leodemoura/lean,leanprover/lean,avigad/lean,fgdorais/lean,UlrikBuchholtz/lean,avigad/lean,leanprover/lean,levnach/lean,fpvandoorn/lean,fpvandoorn/lean,avigad/lean,fpvandoorn/lean,digama0/lean,leodemoura/lean,soonhokong/lean-osx,rlewis1988/lean,avigad/lean,levnach/lean,soonhokong/lean-osx,rlewis1988/lean,digama0/lean,soonhokong/lean-windows,digama0/lean,avigad/lean,UlrikBuchholtz/lean,Kha/lean,soonhokong/lean-windows,fpvandoorn/lean,soonhokong/lean,dselsam/lean,fgdorais/lean,johoelzl/lean,johoelzl/lean,Kha/lean,leodemoura/lean,leanprover/lean,avigad/lean,leodemoura/lean,leanprover-community/lean,levnach/lean,johoelzl/lean,fgdorais/lean,johoelzl/lean,soonhokong/lean-osx,rlewis1988/lean,leanprover/lean,rlewis1988/lean,soonhokong/lean,Kha/lean,soonhokong/lean-windows,rlewis1988/lean,soonhokong/lean,javra/lean,rlewis1988/lean,dselsam/lean,javra/lean,dselsam/lean,leanprover/lean,dselsam/lean,soonhokong/lean,soonhokong/lean-windows,fpvandoorn/lean,digama0/lean,leanprover-community/lean,UlrikBuchholtz/lean,leodemoura/lean,fpvandoorn/lean2,UlrikBuchholtz/lean,fgdorais/lean,johoelzl/lean,soonhokong/lean,fpvandoorn/lean,levnach/lean,fpvandoorn/lean2,fpvandoorn/lean2,fpvandoorn/lean2,UlrikBuchholtz/lean,leanprover-community/lean,javra/lean,Kha/lean,leodemoura/lean,dselsam/lean,leanprover-community/lean,levnach/lean,digama0/lean,digama0/lean,soonhokong/lean-osx,soonhokong/lean-osx,leanprover/lean,soonhokong/lean-windows,Kha/lean,dselsam/lean,fgdorais/lean,javra/lean,johoelzl/lean,fpvandoorn/lean2