Operators in Kotlin, such as
/ for division, map to functions.
/ maps to
for example. We can implement those functions on whatever types we want (directly
or via extension functions), and then we can use the operator for those types.
However, we have to add the
operator keyword to the function declaration,
which works a bit like
override and indicates that we know that we are implementing
a function that is tied to an operator.
Here, we implement
String, to be able to divide a string into a
certain number of pieces.