Add imitation step for equalities.
Add imitation step for equalities.

Signed-off-by: Leonardo de Moura <7610bae85f2b530654cc716772f1fe653373e892@microsoft.com>

Kha/lean,fpvandoorn/lean,Kha/lean,soonhokong/lean-osx,UlrikBuchholtz/lean,leanprover/lean,fgdorais/lean,htzh/lean,htzh/lean,digama0/lean,fpvandoorn/lean2,levnach/lean,htzh/lean,fpvandoorn/lean2,johoelzl/lean,sp3ctum/lean,c-cube/lean,fpvandoorn/lean,fgdorais/lean,codyroux/lean0.1,leodemoura/lean,eigengrau/lean,johoelzl/lean,javra/lean,digama0/lean,avigad/lean,digama0/lean,soonhokong/lean-windows,fpvandoorn/lean,Kha/lean,UlrikBuchholtz/lean,fpvandoorn/lean2,leanprover/lean,soonhokong/lean-osx,c-cube/lean,soonhokong/lean-osx,fgdorais/lean,codyroux/lean0.1,Kha/lean,rlewis1988/lean,leanprover/lean,c-cube/lean,fpvandoorn/lean2,leanprover/lean,htzh/lean,fpvandoorn/lean,digama0/lean,fgdorais/lean,soonhokong/lean,johoelzl/lean,dselsam/lean,leanprover-community/lean,leanprover/lean,rlewis1988/lean,digama0/lean,UlrikBuchholtz/lean,soonhokong/travis_test,soonhokong/lean,dselsam/lean,sp3ctum/lean,leanprover-community/lean,dselsam/lean,rlewis1988/lean,soonhokong/lean-windows,eigengrau/lean,fgdorais/lean,c-cube/lean,leodemoura/lean,dselsam/lean,soonhokong/lean-windows,htzh/lean,dselsam/lean,soonhokong/travis_test,c-cube/lean,avigad/lean,leodemoura/lean,eigengrau/lean,johoelzl/lean,avigad/lean,leodemoura/lean,soonhokong/lean-osx,codyroux/lean0.1,rlewis1988/lean,soonhokong/lean-windows,javra/lean,javra/lean,johoelzl/lean,rlewis1988/lean,leanprover-community/lean,levnach/lean,dselsam/lean,levnach/lean,levnach/lean,avigad/lean,leanprover/lean,leanprover-community/lean,fpvandoorn/lean2,leanprover-community/lean,avigad/lean,Kha/lean,soonhokong/lean-osx,javra/lean,sp3ctum/lean,rlewis1988/lean,leanprover-community/lean,soonhokong/travis_test,sp3ctum/lean,leodemoura/lean,soonhokong/travis_test,eigengrau/lean,johoelzl/lean,UlrikBuchholtz/lean,fgdorais/lean,codyroux/lean0.1,fpvandoorn/lean,leodemoura/lean,javra/lean,soonhokong/lean,eigengrau/lean,soonhokong/lean,UlrikBuchholtz/lean,sp3ctum/lean,fpvandoorn/lean,levnach/lean,avigad/lean,Kha/lean,soonhokong/lean,digama0/lean,soonhokong/lean-windows