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- [Instructor] In this Self Check exercise

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we'd like you to use
some of the techniques

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that you learned in the preceding video.

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First we'd like you create
a function called cube_list,

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which is going to walk through the list

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that it receives as a parameter,

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and for each item in the list

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is going to raise that
item to the third power

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and store the result back
into that element of the list.

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And then we want you to
show what the contents

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of the numbers array that you pass

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into the function is
after the function call.

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Separately we'd also like
you to use an empty list,

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we said to call it characters,

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and the += operator to show

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what gets placed into that list

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when you append the string Birthday

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to the end of the list characters.

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So go ahead and pause the video

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and give those two exercises a shot

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and when you come back
I'll show you the answers.

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Okay, let's go and reveal the definition

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of the cube_list function.

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So here we have a cube_list
function that receives

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a parameter named values.

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By the way, for those of you who are new

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to the Python programming language,

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coming from languages with
required type information

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like Java and C and C++ and C#, again

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there's nothing here that actually says

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this has to be a list.

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Now if you don't give it a
list or a sequence of values

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that this for loop can iterate through,

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that's going to result in error messages

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at run time and similarly,
if you don't give it

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something that's compatible
with the exponentiation operator

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that too could result
in problems at run time.

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But these problems that
are possible are also

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as a result of the flexibility

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of the Python language itself.

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So I can pass anything I
want into this function

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and as long as it's
something that's compatible

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with what I'm doing in this for loop,

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then that item will work
with my cube_list function.

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So let's go ahead and define the function.

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We're simply going to iterate through

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each of the elements in
the list called values

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that we receive, or the
sequence called values,

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and for every item in that list,

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we are going to modify the item

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by raising it to the third power.

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So let's then create our numbers list

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that contains the values
from one through 10,

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as specified in the problem statement,

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and let's call cube_list
with those values.

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Now if this worked correctly,
numbers should contain

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the cubes of these values, so we'll have

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one up to 1,000 in the results,

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and indeed we now have the cubed values.

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Let's take a look at the second exercise

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where we simply wanted to
take the string Birthday

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and concatenate its elements to a list.

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So we said to start by
creating an empty list

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called characters, then we want to do

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the append operation using the +=,

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and again if the left side is a list

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the right side must be some sort

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of iterable sequence of elements.

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So far the types of iterable sequences

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we've looked at are
strings, tuples and lists,

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and in this case we
have string, so whoops!

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So let's execute that, and finally

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let's evaluate characters
so that we can see

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the individual characters
were separated out

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into separate strings, one at a time,

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each of those was appended
to the empty list.