public function head($tag, array $options)
{
if (!isset($this->_strings[$tag])) {
return null;
}
$method = __METHOD__;
$filter = function ($self, $options, $chain) use($method, $tag) {
return $self->invokeMethod('_render', array($method, $tag, $options));
};
$head = $this->_filter($method, $options, $filter);
if ($this->_context) {
$this->_context->head($head);
}
return $head;
}