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[No audio]

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Some functions in Python, such as the

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len function, get only one argument.

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If you try to pass more than one, it will

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return an error, saying that it takes exactly one argument.

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Some other functions, such as isinstance,

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take exactly 2 arguments, 2.

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If you try to pass 3 arguments, or

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just 1, you will get an error.

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Some other functions, such as print,

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[No audio]

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take an indefinite

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number of arguments and you saw how we can

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define such functions with only one or more argument.

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But I haven't still explained how

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to create these kinds of functions.

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Let's create one define, let's call this mean.

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So to calculate the mean of a series of numbers.

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So imagine this was our function.

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We want to pass as many items as we want.

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We actually did create a mean function

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earlier, which we could call like that,

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but it still got only one argument.

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So it was a list, like that.

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It's still one object, one argument.

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In this case, we don't want to pass a list there.

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We want to pass as many items as we want.

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So mean, and then what you do,

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you use the asterisk and then args.

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This can be anything actually, after the Asterisk, any

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variable name would work.

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But it's a good practice

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because every programmer uses args.

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So it's good that you use args

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so others can read your code.

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And you also get used to reading others

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code by using args all the time.

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You know what the others are talking about.

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Now let me show you something before I

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apply the algorithm that calculates the mean.

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[Author typing]

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return args, let's see what we get here.

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Now, let me call the function.

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[Author typing]

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So 1, 3, you can also pass

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strings to whatever you like, like that.

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[Author typing]

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And what you get is actually a tuple

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containing all the items, all the objects that

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you passed in the function call.

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So that actually

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[Author typing]

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is a tuple.

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[No audio]

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So what can we do with that tuple?

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Well we can calculate the sum of args.

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So args is a variable, not asterisk args

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divided by the length of the args.

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In this case, we would get an

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error because we have a there.

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So remove a from there and try again.

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a is a string, so it doesn't make

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sense to have the average of a string.

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So we just created a function with

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an arbitrary number of known keyword arguments

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only. I say only because you

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cannot have keyword arguments here.

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You see, x equal to 3 would not work here.

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If you want keyword arguments, then see the next video.

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[Outro sound]