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- [Narrator] Hi, and welcome back

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to your third programming exercise,

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lists, tuples, and sets.

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This exercise has three
steps, as we've seen.

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Create a list, which must be called

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my_list with three numbers, and the total

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of the numbers added
together should be 100.

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To create a tuple, called my_tuple,

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with a single value in it, so
only one value in the tuple.

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And finally, modify the variable set2,

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which is down here, so
that set1.intersection

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with set2 returns five, 77, nine, and 12.

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Let's start with the
first instruction here.

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Create a list called
my_list with three numbers.

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We know how to create a list.

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It's just a variable, so
we type the variable name,

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equals, and then whatever
it is that's in the list,

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so my_list equals, and
then we know that a list

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uses square brackets, so
we're gonna have an opening

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and closing set of square brackets,

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and inside the square brackets,

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we're gonna have the three numbers.

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And the total of the
numbers added together

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should be the value 100.

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So, if we were to add the
three numbers we're gonna put

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in here, we should get the
value 100, so what do we do?

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Well, there's many things we can do.

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We can do one comma two
comma 97, my apologies,

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and that would give you 100.

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We can do 100, zero, zero, and
that would also give you 100.

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So, it doesn't matter what three values

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as long as there are
three numbers in there

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and the total is 100.

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The next is to create
tuple called my_tuble,

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with one single value in it.

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Now, this trips up a lot of people,

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because we can create
the my_tuple variable

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and then we know that tuples use

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normal brackets instead
of square brackets,

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so we put in our opening
and closing set of brackets,

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and then we put a value in
it, like 15, for example.

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And now, a lot of other
students fall for this.

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This is not a tupble.

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Sadly, brackets around
the 15 is not a tuple.

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This is the brackets that would be

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in a mathematical equation.

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For example, you might have
15 times two minus 10, say.

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And what the brackets mean
here is that the 15 by two

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happens before minus 10,
which it would anyway,

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but nevertheless, these brackets here are

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for mathematical preference only.

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They do not signify a tuple.

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So, this is slightly confusing.

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Now you may wonder, well, how
do we define a tuple then,

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and the way you define a
tuple is by making sure Python

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understands that this is
not a maths equation here,

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no mathematics is happening in this tuple,

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so we put a comma, which is
not a mathematical symbol,

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and now this tells Python,
okay, this is a tuple,

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it has the brackets and
it has a value in it,

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and then it has a comma,
which tells us that there

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may be other values behind
it, even though there are not.

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And this tells Python
that this is now a tuple.

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Optionally, because this feels a bit weird

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and a bit redundant, we can also

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just remove the brackets
and just have 15 comma,

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and now Python realises that
this is a single-value tuple.

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So we can do that too.

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Finally, we're gonna modify
set2, this variable here,

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so that set1.intersection set2
is five, 77, nine, and 12.

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The intersection between two sets

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are the values that are in both sets.

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So, in order to make set1
intersection set2 equal

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five, 77, nine, and 12, all we have to do

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is make sure that set1 and
set2 have these values in them.

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And as you can see, set1 has the values

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five, 77, nine, and 12,
so all we have to do

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is make set2 have those values too.

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So, five, 77, nine, and 12.

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And then we can check the solution,

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and they should tell us
that it is all correct.

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Now, there we are.

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So now we have created a
list with three values,

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the total of which equals 100,

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a single-value tuple, and we've looked

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at a couple of potential
problems we can encounter

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with that tuple, and finally
we've looked at modifying

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the set variable, so that the intersection

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of the two sets returns a specific set.

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That's everything for this video.

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I'll see you on the next one.