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Speaker 1: Let's talk about something called

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arguments and keyword arguments.

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I mean, we've already seen that before, right?

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With a function we actually have the special characters that

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we can use called args and star star keyword args.

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How can we use these?

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Well, let's have a look.

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Let's try and have a function, let's say define,

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and we'll call this a super_func, for super function,

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that receives some sort of arguments.

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And these arguments that we're gonna receive,

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and remember, although I'm calling these args,

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this itself is a parameter, remember?

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But let's say that we wanna just return

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sum of the arguments.

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And you might be wondering, wait, whoa, sum?

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Don't we have to define that function?

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Well, sum actually exists in Python,

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as you can see over here.

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So we can just return the sum of the arguments.

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So let's try this.

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Let's say super_func and give it arguments (1,2,3,4,5).

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If I click run,

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hmm, I get an error.

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Super_func takes one positional argument,

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but five were given.

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And that makes sense, right?

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Like I only have one parameter here,

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which is a positional argument that it accepts.

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And I'm trying to sum this,

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so it only receives one but I'm giving it

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to all these things that it doesn't know about.

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And this is where we can use something like this

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by adding a star to here.

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We're saying hey, this can accept any number

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of positional arguments like this.

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As many as I want.

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As a matter of fact, let's print this out.

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If I do print(*args) and we run this function,

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we see that the print(*args)

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gives us one, two, three, four, five.

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These are all the parameters or the arguments that we get.

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And if I actually remove the star here and click run,

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look at that.

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I actually get this as a tuple.

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So args inside of this function is a tuple of arguments

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that I give it. (1, 2, 3, 4, 5).

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So sum of the tuple (1, 2, 3, 4, 5) is going to

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give us the right answer.

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It's going to print for us

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the answer, 15.

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Very, very cool.

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So this way we can extend and use our *args to have

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in a function that can accept any number of arguments.

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So what is this one now?

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Well, this one allows us to use keyword arguments.

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For example, let's say I have the **kwargs like this.

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And by the way, this can technically be anything.

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So this is a variable that we're creating,

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so I can name it hoooooo if I wanted to,

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but the standard is to name it args and kwargs.

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Because other developers are using it this way

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and it's just the way it's done in the Python community.

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Now, with the kwargs, as you might have guessed,

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I can add keywords

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like num1=5

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and then num2=10.

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So that if I print the kwargs and I click run

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I get a dictionary of num1 equals to five

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and num2 equals to 10.

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So I can actually do something like sum plus sum

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of items in the kwargs

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and grab the values, right?

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We've seen that before.

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And let's actually grab this and do a for loop

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and say items in kwargs.values, remember?

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To grab the values over here, and in here just

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add up the totals.

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So let's say that in here

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total equals or plus equals items.

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And we'll add a total in here that is initially zero.

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So that sum will be sum(args) plus total.

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If I run this,

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I get 30,

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which looks about right.

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Now, this does look a little confusing. So let's go over it.

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We have the *args which allow us to grab these

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positional arguments and just sum everything.

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And we also have kwargs which allow us to grab any number of

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keyword arguments and get a dictionary,

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which comes as kwargs, and then use them however we want.

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In our case, we're looping over all the values,

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so items in kwargs.values.

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And then I'm just going to total all those items,

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have a total and just return the sum.

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Now this is, again, extremely useful

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because our super_func can now take as many arguments,

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as many positional and keyword arguments as we want.

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Now, one final thing.

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There is a rule of the ordering that we can do

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of our parameters here, right?

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So the order, the rule is this.

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First in our parameters we have, well, our actual params.

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Then we can do *args,

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then default parameters,

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then **kwargs.

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Let me show you what I mean.

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If we wanna define this function, we wanna make sure

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that if we give it a parameter of, let's say name,

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that should come before *args.

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And if we have default parameters, that should usually come

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after args, but before kwargs.

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So if I do, let's say i='hi'

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and make sure we add a comma here.

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We now have, following the rule, and by the way

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you would never actually write a function like this

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because, well, frankly, it looks super confusing.

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Usually you're only using two of these

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or maybe just one of these.

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But this way I can call this function with name, Andy,

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then my args, then my default parameter,

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which will be i equals to 'hi',

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which let's say we don't even pass in.

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And then we have this.

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So if we run here, this still works.

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We are just not using name and i,

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but you see that I'm following the rule of params,

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args, default parameters, and then kwargs.

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All right, hopefully your head doesn't hurt too much

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after this one.

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Take a break and I'll see you in the next one.

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Bye-bye.