code: protected function findSlotsInTemplates()
      {
          $templates = $this->findTemplates();
          $slots = array();
          foreach ($templates["base"] as $templateName => $templateFile) {
              $templateContents = FilesystemTools::readFile($templateFile);
              $slots = array_merge_recursive($slots, $this->findSlots($templateName, $templateContents));
          }
          $baseSlots["base"] = $slots;
  
          $slots = array();
          foreach ($templates["template"] as $templateName => $templateFile) {
              $templateContents = FilesystemTools::readFile($templateFile);
              $slots[$templateName] = $this->findSlots($templateName, $templateContents);
          }
  
          return array(
              'base' => $baseSlots,
              'templates' => $slots,
          );
      }
docs: Find the slots parsing the theme's templates
  
  @return array