$student1->drop_courses(["C++"]);
$student1->drop_courses(["C++", "Bio"]);


##</code><code>##

sub drop_courses { # drop_courses(["",]);
  my $self=shift;
  my $del_cour = shift; # $del_cour = ["Java"];
  my $num = @{$del_cour};
  if ($num == 1) {
     @{$self->{'Course(s)'}->{'cour'}} = 
         grep { $_ ne $del_cour->[0] } 
             @{$self->{'Course(s)'}->{'cour'}};
print "After dropping: ", 
  join (", ", @{$self->{'Course(s)'}->{'cour'}}), "\n";
} elsif ($num > 1) {
  for ($i=0; $i<$num; $i++) {
    @{$self->{'Course(s)'}->{'cour'}} = 
      grep { $_ ne $del_cour->[$i] } 
          @{$self->{'Course(s)'}->{'cour'}};
  }
}
print "After dropping: ", 
  join (", ", @{$self->{'Course(s)'}->{'cour'}}), "\n";
}