my $debug = 5;
print STDERR "Looking for id $courowid \n" if $debug > 8;
while (<FILE>) {
  chomp;
  my ($id, $course) = split(/\t/);
  print STDERR "trying id $id, course $course\n" if $debug > 8;
  if ( $id == $courowid ) {
    print STDERR "found id $id, course $course\n" if $debug > 5;
# if we match the ID, push the course name onto the 
# the array in the coudata hash, key $id
    push @{$coudata{$id}}, $course;
  }
}
print header;
if ( %coudata ) {
      # found, display data by taking each course back outof
      # the array
  foreach my $id ( keys %coudata ) {
    print STDERR "show id $id\n" if $debug > 6;
    foreach my $course ( @{$coudata{$id}} ) {
      print STDERR "show id $id, course $course\n" if $debug > 8;
      print ul("$id: $course");
    }     # foreach my course 
  }       # foreach my id
}else {
      # not found, show error
      print h1("Can't find row '$courowid'");
}