fix(basics): add extra space
fix(basics): add extra space

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