public function downVote(Comment $comment)
 {
     $post = $comment->post()->get()->first();
     $user_up_vote = Comment_Vote::where(['comment_id' => $comment->id, 'user_id' => Auth::id(), 'up' => 1])->first();
     $user_down_vote = Comment_Vote::where(['comment_id' => $comment->id, 'user_id' => Auth::id(), 'up' => 0])->first();
     if (!$user_down_vote) {
         if ($user_up_vote) {
             $user_up_vote->delete();
         }
         return $this->vote($comment, 0);
     } else {
         return redirect()->route('posts.show', compact('post'))->with("warning", "You 've already downvoted this comment");
     }
 }
 public function downVotes()
 {
     return Comment_Vote::where(['up' => 0, 'comment_id' => $this->id])->count();
 }