code: protected function addBlockToSlot($dir, array $options)
      {
          $slot = $this->getSlotDefinition($dir);
          $blocks = $slot["blocks"];
          $blockName = $options["blockname"];
          $position = $options["position"];
          array_splice($blocks, $position, 0, $blockName);
  
          $slot["next"] = str_replace('block', '', $blockName) + 1;
          $slot["blocks"] = $blocks;
  
          $this->saveSlotDefinition($dir, $slot);
  
          return $blockName;
      }
docs: Adds a default block to the given slot
  
  @param string $dir
  @param array $options
  
  @return string