fix(12): "open classical" and "data.subtype" were moved to init
fix(12): "open classical" and "data.subtype" were moved to init

cjmazey/fork_leanprover_tutorial,Hodapp87/cs6460_project,leanprover/tutorial,soonhokong/lean-tutorial,Hodapp87/cs6460_project,cjmazey/fork_leanprover_tutorial,avigad/tutorial,avigad/tutorial,fpvandoorn/tutorial,leanprover/tutorial,fpvandoorn/tutorial,soonhokong/lean-tutorial,Hodapp87/cs6460_project,soonhokong/lean-tutorial,avigad/tutorial,cjmazey/fork_leanprover_tutorial,leanprover/tutorial,fpvandoorn/tutorial