code: function _add_permanently_to(stack, item_or_list){
  	if( item_or_list && tcache[stack] ){
  	    if( ! us.isArray(item_or_list) ){ // atom
  		tcache[stack].push(item_or_list);
  	    }else{ // list
  		tcache[stack] = tcache[stack].concat(item_or_list);
  	    }
  	}
  	return tcache[stack];
      }
docs: Permanently push an item or a list onto the internal list structure. Changes structure.