repetition operator in perl

Another very handy operator is the repetition operator. Let's say you want to underline some output. You might be tempted to code it like this:
    $underline = '--------------------';
    print $underline;
But Perl lets you define a single character and then how many times you want to repeat it:
    $underline = '-' x 20;
    print $underline; # displays '--------------------'