$keys{'C10'}->{'C10-1'}=1;
$keys{'C10'}->{'C10-2'}=1;
$keys{'C10'}->{'C10-20'}=1;
$keys{'C10'}->{'C10-3'}=1;

$keys{'C200'}->{'C200-1'}=1;
$keys{'C200'}->{'C200-20'}=1;
$keys{'C200'}->{'C200-3'}=1;
$keys{'C200'}->{'C200-21'}=1;

$keys{'C30'}->{'C30-1'}=1;
$keys{'C30'}->{'C30-2'}=1;
$keys{'C30'}->{'C30-30'}=1;
$keys{'C30'}->{'C30-4'}=1;

# Result should be :

'C10' => HASH(0x1832a58)
   'C10-1' => 1
   'C10-2' => 1
   'C10-3' => 1
   'C10-20' => 1
'C30' => HASH(0x1832b30)
   'C30-1' => 1
   'C30-2' => 1
   'C30-4' => 1
   'C30-30' => 1
'C200' => HASH(0x1835318)
   'C200-1' => 1
   'C200-3' => 1
   'C200-20' => 1
   'C200-21' => 1