Process theme variables for a specific theme hook.
This hook allows modules to process theme variables for a specific theme hook. It should only be used if a module needs to override or add to the theme processing for a theme hook it didn't define.
For more detailed information, see theme().
$variables: The variables array (modify in place).
Note: this list is generated by pattern matching, so it may include some functions that are not actually implementations of this hook.
function hook_process_HOOK(&$variables) {
// @todo There are no use-cases in Drupal core for this hook. Find one from a
// contributed module, or come up with a good example. Coming up with a good
// example might be tough, since the intent is for nearly everything to be
// achievable via preprocess functions, and for process functions to only be
// used when requiring the later execution time.
}