global results = ();
function match (people) {
  if (people.empty) {
    return SUCCESS
  }
  $x = people.pop;
  foreach $y (people) {
    if (validpair($x, $y) {
      if (match(people.remove($y)) == SUCCESS) {
        results.push( {$x, $y} );
        return SUCCESS;
      }
    }
  }
  return FAILURE;
}