It's awkward and error-prone to use slicing to delete things out of a list.
So, Python gives us a special operator to do that it's called the delete operator, del.
In this case, in this code we're creating a list called
a with three items in it: one, two and three.
And then we're calling the del operator to remove item one.
So, let's see this in CodeLens.
We first create the list and then a square bracket one refers to this position,
and when we delete it the value three is now going to move
up into position one and we'll end up with just one and three in our list.
Now we've just got one and three and we can not just delete a single item,
we can delete a whole sequence of items.
Here we have a list: a, b, c, d,
e and f. We're going to start at position one,
go all the way up to but not including position five.
Now it's a list, square bracket one,
colon five and that's all going to be deleted.
So, do that and we're left with just a and f.