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Welcome back.

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Let's keep going with some more stirring methods now we've learned about adding and removing ones.

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We learned about append, insert and extend and then removing.

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We learned about pop, remove and clear.

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There's a few other important ones.

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Let's go with the index.

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So instead of clearing here, let's clean this up.

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And we'll do basket dot.

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An index, as you can see, we give it a value, a start and a stop, what does that mean?

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Well, we want to say, hey, what index is number two?

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If we do index of two and I click run.

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It's going to give me one I know this is a little confusing, but it's asking for the index.

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Where is number two?

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Number two is that index of one, let's change these into letters just so it's more clear.

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So we have A B.

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D and then finally, E!

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And again, if I do.

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D here and I click run.

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I get an index of three because zero one, two, three, it's on shelf three in our memory and you can

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also do a optional parameter here, which is where should we start looking?

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So I want you to start looking at index of zero and then finish looking at index of two.

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If I do run here, I get an there.

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It says, hey, D is not enlist because while we started at index of zero and stopped it index of two.

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If I do three and I click run.

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No, it stops right before 3:00, so if I do for.

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And I click Ron.

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There you go.

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I get three.

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Now, errors are not good in our programs.

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Ideally, we don't want to get errors, so how do we avoid this?

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What if we're looking for something and we're not sure if it's in the list or not?

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There's another nifty way of looking for things in a list.

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And this involves what we call a python.

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Key word.

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A key word is something that you use in Python that, well, already has some meaning.

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For example, a key word here, if I go to Python, key words are all these words that already mean

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something.

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Now we're going to go through them and we haven't seen a lot of them yet.

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But you might have seen true right in boolean values to mean something.

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So in Python, we can't really use the word true because, well, it already means something.

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There's a word called in that, as you can see, as soon as we type means something as a key word in

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Python and this is quite nice, we can say, hey, is D. in the basket and if I run this.

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I get true, OK, is X in Baskett.

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I get false because, well, it doesn't exist and this is actually quite useful and we can even do it

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for strings.

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For example, if I'm looking for, let's say, the letter, I in a word and let's say it's in.

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Hi, my name is Ian.

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If I click, run.

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I get true because the letter I.

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Does exist in this drink.

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All right, let's learn another one.

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Another one is basket dot count.

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And we can count how many times an item occurs, so, for example, if I do D and I click run.

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I get one because D only exists once in the list, but if I add another D in here and I click run.

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We get to it counts how many time this value occurs in our list, a very, very useful.

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All right, a few more still to go.

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Let's do some exercises and I'll see you in the next one.