protected function pushBlock($selectors = null, $type = null)
{
$b = new \stdClass();
$b->parent = $this->env;
$b->type = $type;
$b->id = self::$nextBlockId++;
// TODO: kill me from here
$b->isVararg = false;
$b->tags = $selectors;
$b->props = array();
$b->children = array();
$this->env = $b;
return $b;
}