[15] Make a program that will print the following hash's data sorted in case-insensitive alphabetical order by last name. When the last names are the same, sort those by first name (without regard for case). That is, the first name in the output should be Fred's, and the last one should be Betty's. All of the people with the same family name should be grouped together. Don't alter the data. The names should be printed with the same capitalization as shown here. (You can find the source code to create a hash like this in the file sortable_hash with the other downloaded files.)
my %last_name = qw{
fred flintstone Wilma Flintstone Barney Rubble
betty rubble Bamm-Bamm Rubble PEBBLES FLINTSTONE
};