Making changes to a nested array that may have arrays or strings in some values

Pulled this from the test module for the new RDF module we're putting in Drupal core.

// dealing with a nested array where the top level can be a string or an
// array is complex and helper functions may be a good addition

<?php
  rdf_mapping_alter_create('rdf_test_container', 'title', )

/**
 * Make adding an attribute and property sane.  $prop can be an array.
 */
function rdf_mapping_alter_create($container, $attr, $prop, &$mapping) {
  if (isset($mapping[$container])) {
    if (isset($mapping[$container][$attribute])) {
      $mapping[$container][$attr] = (array)$mapping[$container][$attr];

//      isset($mapping['rdf_test_container']['created'][

  // @TODO test this
  // what happens if we try to unset something that isn't there?
  unset($mapping['rdf_test_container']['not_there']); 
}
?>

Resolution