#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

my %color_of = (
    apple   => 'red',
    orange  => 'orange',
    grape   => 'purple',
    tomato  => 'red',
    lettuce => 'green',
    peanut  => 'tan',
);

my $previous;
for my $fruit_or_vegetable (
    sort { $color_of{$a} cmp $color_of{$b} } keys %color_of
) {
    say "$previous before $fruit_or_vegetable" if defined $previous;
    $previous = $fruit_or_vegetable;
}