feat(frontends/lean/decl_cmds): minor modifications for supporting mutually recursive functions
feat(frontends/lean/decl_cmds): minor modifications for supporting mutually recursive functions

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