package X;

use strict;

sub printlist {
    my ($self, @L) = @_;

    for my $prop (@L) {

        if ($self->{established}->{$prop}) {
            warn "$prop established";
        } else {
            warn "$prop NOT established";
        }
    }
}
my $self = {} ;

bless $self, 'X';

my @L = qw(intro_cs comp_org adv_prog theory);
my @M = qw(intro_req);

$self->{established}->{$_}++ for @L;

$self->printlist(@L);

$self->{established}->{$_}++ for @M;

$self->printlist(@M);