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OK, now we want to start to talk about the forward and the back buttons, and these are also a little

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bit tricky.

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So just sort of think about it.

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How would you make a forward button and a back button go if you know that the current song is no win

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and you said play the next song.

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Well, what is the next song North?

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How do we know that?

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We don't know which song is in the list?

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We have no idea.

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But what we do know is the number.

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So each of these items are numbered like a python list.

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So this first one is zero.

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This one's one, two, three, four or five.

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So we could say, hey, play the current song plus one to go forward or we can say, hey, play the

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current song, minus one to go back.

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And we don't really need to know what the names of the songs are.

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We could just use those numbers.

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So in a nutshell, that's what we're going to do.

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So let's start to do that.

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So head over to our code and I'm going to call these next song and previous song functions.

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So let's come down to our buttons.

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So we've got the back button and the forward button.

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Let's do the forward button first.

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So let's go command.

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Equals next song.

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OK, so let's not create that guy so down here below.

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Let's go to.

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Create function to play the next song, and we want to define next song, we're not passing anything

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into it, so.

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Let's get current song number so that one and I'm going to call this next so or next song.

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Well, we don't want to call the next song because we call this function next song.

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Let's call it next one.

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Right.

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All right.

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So that will be remember, our playlist is called The Playlist Box, so we can reference it by calling

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playlist box dot.

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We can get the color selection.

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So this will tell us what the current selection is that we've highlighted that the green bar is on,

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so remember are a little label guy here.

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We're going to use this a lot.

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Let's go ahead and look and see what that is actually returning.

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So let's go my label dot config and set the text equal to next underscore one.

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So we just want to see what this is.

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So let's go and save this and run it.

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So let's add a bunch of songs.

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So let's click on this one, the very first one now, if we click the next button right here, you see

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it return zero.

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Remember, this is the zero one.

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This one is one.

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So we can click here and boom.

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Now one, this one is going to be the last one.

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So zero, one, two, three, four, five.

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This should return five, boom five.

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So we've got a number so we can say, hey, now play this number plus one.

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You know, we're currently on this zero.

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We want to play the next one, which will be zero plus one, which is one, which is this one makes

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sense.

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So, OK.

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Let's get rid of this label.

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We don't really need it, so we want to set the next one as the next one.

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So let's go next.

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Underscore one equals next.

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Underscore one.

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And let's go zero.

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Plus one now.

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This is a little confusing because this number zero is not zero, right?

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I'm calling this because.

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This doesn't really return a no, it looked like it did when we just looked at it, it was returning

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zero or one or five or whatever, but that wasn't a number.

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That was a list with a number in it.

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And we can actually see that by printing this out.

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So let's go print next, underscore one.

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This will print it to the actual terminal.

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So let's just save this really quickly and run this one more time.

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And let's add some songs.

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This one is the fifth one, and if we click this, nothing happens, but when we close this, we can

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see down here in the terminal it's returning a python tuple or a python list and tuples or the same

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thing, basically, almost.

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But you can see it's ordered it's got five.

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That's the thing.

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The song number is five, but it's in a tuple.

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So to access five, we we have to call the zeroth item from the tuple.

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Right.

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The zero with item here is five.

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So does that make sense.

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So since this is returning as it sort of a tuple as a list, we have to call, you know, to get five,

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we have to call the zeroth item to do that.

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We call.

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Let's get right to this.

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We call the zeroth item of the list, which will return whatever this current selection is, then we

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want to just add one to it, right?

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So if we're on song number three, next one will end up being four.

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Right.

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And let's come at this for good measure.

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Let's go add one to the current song number.

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The this thing.

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OK, so this video is getting a little bit long, I think we'll stop right here and pick this up in

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the next video.