 So here's an implementation of a skip list that is a little bit more robust. Let's say, for example, I wanted to do a lookup of 25. Go ahead and pause this video and see if you can kind of implement it for a second. Three, two, one. Okay, so you've paused that video, you've looked at it. The first thing, once again, is I'm starting at this as my sort of start point. It's negative infinity, so I already know that it won't equal this. The first thing I ask is, is it equal to it? Because I know. Well, no. Well, I have to look at my next. Is this equal to my 25? No. Is it less than my 25? Is 25 less than positive infinity? Yes, it is. So what do I do? Wherever I was, I go down a level. As a result, this is my new... It's no longer a starting point, but this is actually the position in the skip list I'm at now. The same approach is going to come into play. Is this equal to 25? No. What about my next? Well, that's 17 this time. Let me actually... Is 17 equal to 25? No. Is 25 less than 17? No. What this means, instead of going down like I did when I saw my yes, this means I go over. And so 17 is going to become my new position. Same kind of concept comes into play. Now that this is my new position, I look at my next. Is 25 equal to positive infinity? No. Is 25 less than positive infinity? Yes, it is. So what do I do? I go down again. And this 17 has become my new approach. Well, now that I've taken this look, I say, what's my dot next? And I'll change colors just for that sake. This is my new position. I look over to my next. And does that equal what we were looking for? 25? Yes, it does. So we would return. Excellent. Let's say for the sake of practice, instead of a lookup of 25, I did a lookup of 26. Now, we can very quickly see that 26 is not in my skip list. So how would this get implemented? So I'm at 25. I do my 25 comparison to 26. It doesn't equal each other. I then come over. Is 25 equal to 55? No. 26 is less than 55. So what do I do? I go down again. And new color. That becomes this. I do my next lookup, which is 31. Is this 26? No. So is 26 less than 31? Yes. So what do I do? I go down. I change my color. I'm actually going to do the same comparison because I'm on a new level. So I still have to do it. 26 still less than 31? Yeah, it didn't change. And math did not change in that lookup period. But I come here. This is interesting because now I'm at the last level of my skip list. I'm not here. I'm not here either since this still doesn't work. And so as a result, we would return no. Because it does not exist inside of our skip list.