code: public function checkboxFilled($options = [], $enclosedByLabel = true)
      {
          Html::addCssClass($options, $this->checkboxFilledCssClass);
          return parent::checkbox($options, $enclosedByLabel);
      }
docs: Renders filled in checkbox
  @see http://materializecss.com/forms.html#checkbox
  @param array $options
  @param bool|true $enclosedByLabel
  @return $this