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[MUSIC]

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Hey, my name is Ashley Boucher and
in this course,

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we're gonna be diving
deeper into functions.

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You might have touched on functions
previously in your coursework, but

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before moving on, be sure to check
the teacher's notes to make sure you've

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covered all the prerequisites for
this course.

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Also, don't forget that you have complete
control over how you watch this video.

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Want to slow me down or speed me up?

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Go for it, feel free to pause, rewind,
or even fast-forward as necessary.

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So what's a function?

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A function is
a reusable block of code.

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You write a block of code,
give it a name, and

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then you can call the block of
code whenever you need to use it.

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Typically, a function does one programming
task and it does it really well.

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That's the standard we're looking for,
in other words,

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you should be able to think of a short and
descriptive name for your function.

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If you can't do that,
the function is probably doing too much.

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One thing developers should always
try to do is not repeat themselves.

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This is known as DRY programming or
Don't Repeat Yourself.

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Functions are great way to help us
avoid writing the same code over and

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over because we can just call the function
whenever we need to execute that code.

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Another equally important
reason to use functions is

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that they make your code easy to read and
follow, they also make easy to test.

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Sure, you could write your code for

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program in one script file without any
functions, but what if there's a bug?

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How would you ever find it let alone
squash it, and how would anyone also

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working on your code
know what it was doing or

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make changes to it without
breaking something?

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Functions are everywhere in programming
and they are very important, so

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let's learn more about them.