def blog__clean_post_parents
      post_parents = LatoBlog::PostParent.all
      post_parents.map { |pp| pp.destroy if pp.posts.empty? }
    end
def blog__clean_post_parents
      post_parents = LatoBlog::PostParent.all
      post_parents.map { |pp| pp.destroy if pp.posts.empty? }
    end
This function cleans all old post parents without any child.