All right! Time to add in a little control flow.
For the if half of our branch, we want to check whether the user's input contains an "s".
if string_to_check.include? "substring"
We can do that using Ruby's .include? method, which evaluates to true if it finds what it's looking for and false otherwise.
(As a general rule, Ruby methods that end with ? evaluate to the boolean values true or false.)