package Student3; 
sub new { my $class = shift; my $ref = {}; 
  # Anonymous hash 
bless($ref, $class); 
return $ref; } 
sub set_student { 
my $self = shift; 
<...continues...>
print "Enter the student's course(s) delimiting them 
  with a comma (,) "; 
chomp(my $cour = <STDIN>); 
$cour =~ s/\s+//g; 
my @cour = split(",", $cour); 
chomp($self->{"Course(s)"}->{"cour"}=[@cour]); 
<...continues here...> 
} 
<...continues...>
sub drop_courses { 
   my $self=shift; 
   my $del_cour = shift; 
                   # $student1->drop_courses(["C++"]); 
   my $num = @{$del_cour}; 
   if ($num == 1) { 
       foreach $k (@{$self->{'Course(s)'}->{'cour'}}) { 
         if ($k eq $del_cour->[0]) { 
                $k=""; 
         } 
        } 
} 
print "After dropping: ", 
     join (", ", @{$self->{'Course(s)'}->{'cour'}}), "\n"; 
1;