WEBVTT

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Alright, we are back, and I hope you did that little exercise, because it was very simple.

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You just needed to replicate it to the other colored buttons.

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So here's what I'm going to do.

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First, I'm going to solve this little exercise.

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So I'm going to go to the red button, and I'm going to drag this code to, for example, the orange sprite.

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This will duplicate the code inside the orange sprite as well.

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So I'm going to release the mouse, and I'm going to go to the orange sprite,

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and notice that this code was duplicated inside the sprite as well.

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Now, instead of broadcasting red for orange, I'm going to broadcast a new message.

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So in the drop down, I'm going to select a new message.

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I'm going to name this orange.

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Now, I'm going to go to pencil, and I'm going to right-click on the small piece of code,

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and I'm going to click duplicate.

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So when I receive, in this case, orange, I'm going to set the pink color to the appropriate orange color.

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So I'm going to hit the eyedropper, and I'm going to select that orange color in the button.

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And I'm going to do the same for all the other colored sprites now.

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So I'm going to fast forward a little bit.

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All right, so I have every single button sending a new message when it's clicked.

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Now, I'm going to make the pencil receive those messages,

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and set the pen to the appropriate color.

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Again, a little fast forward.

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Okay, all right.

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So we have small scripts here for every single color for the pencil.

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When any one of these colored buttons is clicked, they will broadcast a different message,

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and the pencil will react to every single one of those messages by setting its pink color to a

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different color. Let's test it out. So if I stop and start the application again,

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the pencil starts with black. But let's change the colors.

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So red, orange, yellow, green, blue, indigo, and violet.

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So all the colors are working properly.

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Now let's focus on the buttons on the second layer.

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Now we're going to program those, and I'm going to start with the magic wand,

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whose purpose is to erase what we've drawn on the stage.

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Now, you might think that erasing colors selectively here on the stage might be complicated,

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but it's actually not. It's basically drawing white on the stage.

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It's the same as erasing, because the background is white.

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So the user of this application will not be able to tell if we're erasing the color

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or just drawing white on top of it. So we're just going to use this dirty little trick.

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All right, so when we click on the magic wand, the erase button,

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we're just going to broadcast a message to the pencil to switch the costume to the magic wand

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and just draw white on top of it. That is set its pencil color to white,

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so I'm going to go to events when the sprite is clicked.

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I'm going to zoom this in a little bit, so when the sprite is clicked,

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I'm going to broadcast a new message. So I'm going to broadcast a new message.

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I'm going to call this magic wand.

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Okay, and pencil the pencil sprite. When it receives the magic wand,

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it will change its costume and set the pink color to white.

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So when I receive the magic wand message,

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I'm going to set the pink color to white,

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so I'm just going to right click and duplicate it.

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Or you might want to drag it from the pen section here

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and then click inside the set pen color to

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and drag the second slider all the way to the left and the third slider

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all the way to the right to make the color complete.

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Only white. Okay, then go to the look section and make the pencil sprite.

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Switch its costume to magic wand.

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Okay, so if I start the application again,

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I can draw something on the screen.

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And if I hit the magic one button,

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notice that it changed its costume.

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And if I draw on top of it,

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notice that it starts erasing stuff.

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Now let's implement a similar mechanism for the pencil button over here.

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So I'm going to click on the draw button

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and I'm going to go to events.

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And when the sprite is clicked,

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I'm going to broadcast a new message

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that I'm going to name pencil

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and the pencil sprite.

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When it receives the pencil message,

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it will set its pen color to black

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and switch its costume back to the pencil.

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So I'm just going to duplicate this little script.

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So when I receive the pencil message,

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I'm going to set the pink color to

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and I'm going to drag the third slider all the way to the left

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until the color becomes black.

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Okay, and then switch its costume to pencil.

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All right, so let's play around with the application a little bit.

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So right from the start,

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I have something to fix because the default costume for my pen

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is not the pen.

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It's the magic wand.

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And if I start drawing,

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we have the magic wand costume,

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yet we're still drawing on the stitch.

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This is wrong.

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So I'm going to stop the application

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and right at the beginning,

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when the flag is clicked,

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I'm going to set the costume to pencil.

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So I'm going to go to looks

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and I'm going to switch the costume to pencil.

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So if I start this again,

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notice that the costume went back to pencil.

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So if I hit the magic wand,

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it's able to delete.

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And if I hit one of the colors,

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well, this is wrong

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because we still have the magic wand costume,

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yet we can draw in different color.

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So this is again wrong.

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We need to fix the pencil sprite to switch its costume back to pencil,

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when we click either of the colorid buttons.

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So I'm going to switch costume to pencil B,

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when I receive any one of the colorid messages red,

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orange, blue, and so on and so forth.

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So I'm going to add the purple code block

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in every single one of the receive scripts.

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So I fast forward a little bit.

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If I'm going too fast,

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feel free to pause the video

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and add the purple block

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to every single one of your colored receive scripts.

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All right.

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But right now, I'm going to test the application

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and notice that when I have the magic wand

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and switch back to a colored block,

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the costume is switched back to pencil

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and the color is the correct one.

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All right.

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So we have three more buttons to go,

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which fortunately are going to be pretty easy to program.

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Let me click, for example, on the grow button.

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So when the grow button is clicked,

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we'll need to tell the pencil to increase its pen size.

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Now you're already familiar with sending messages,

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so that means broadcasting a new message,

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but the pencil will react and increase its pen size.

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So I'm going to go to events,

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and when this spread is clicked,

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I'm going to broadcast another message,

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and I'm going to name this grow pen size.

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Okay, and the pencil sprite will react to that

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by saying when I receive grow pen size,

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I'm going to go to the pen section

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and I'm going to add the screen change pen size by one.

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This is exactly what I want,

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and in a similar fashion,

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the shrink button will act in the same way.

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So when this sprite is clicked,

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I'm going to broadcast a new message,

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and I'm going to name this shrink pen size.

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All right, and we'll make the pencil react to that,

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and I'm simply going to duplicate this last script that I wrote.

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And instead of group and size,

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I'm going to select shrink based size.

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Instead of changing pen size by one,

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I'm going to change it by negative one,

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which means I'm decreasing the pen size.

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So let me test this out,

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so I'm going to stop the application and start it again.

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And I'm going to draw a few things on the screen.

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I'm going to select a different color,

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and I'm going to click this groove button a bunch of times.

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So 1, 2, 3, 4.

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Notice that when I draw again,

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the line is so much thicker,

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which means that the messages had the desired effect.

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Let me click on another color

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and click the shrink button size a bunch of times,

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and notice that the pen size is so much thinner now.

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Cool.

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So we have four out of five buttons working nicely.

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The last button is the easiest of all this erase all button.

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So when this button is clicked,

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we want every single mark on the screen erased,

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and this is very, very easy.

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When the sprite is clicked,

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we want the pen to erase all the marks on the screen,

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and that is it.

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So if I stop and start the application again,

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and if I draw a bunch of things on different colors,

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and if I hit this button,

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everything will go away, ma'am.

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And at this moment,

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I am glad to see that we are done.

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We have a fully functional paint and draw application

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that you created from Absolute Scratch.

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And I'm very proud of you and what you've learned here.

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So you created your own sprites.

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You'll learn about the pen tool.

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You made it follow your mouse with just a tiny little script.

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And very importantly,

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you've learned that sprites can broadcast

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and can receive messages

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and be programmed to react to them.

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This is something that we'll use

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throughout the rest of the course,

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and all the complex schemes that we'll create

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will rely on messages.