my $test = (
    'a' => {
        'identifiers' => {
                                  'mrt1' => 1,
                                  'mrt2' => 1,
                                  'mrt3' => 1,
         },
    },
    'b' => {
        'identifiers' => {
                                  'mrt2' => 1,
                                  'mrt3' => 1,
                                  'mrt6' => 1,
         },
    },
    'c' => {
        'identifiers' => {
                                  'mrt1' => 1,
                                  'mrt2' => 1,
                                  'mrt3' => 1,
         },
    },
    'd' => {
        'identifiers' => {
                                  'mrt2' => 1,
                                  'mrt3' => 1,
                                  'mrt6' => 1,
         },
    },
    'sum_ab' => {
        'values' => {
                                  'a' => 1,
                                  'b' => 1,
         },
    },
    'sum_cd' => {
        'values' => {
                                  'c' => 1,
                                  'd' => 1,
         },
    },
    'sum_abcd' => {
        'values' => {
                                  'sum_ab' => 1,
                                  'sum_cd' => 1,
         },
    },
);