code: public function setDefaultOptions()
      {
          foreach ($this->_defaultOptions as $k => $v) {
              if (!array_key_exists($k, $this->_options)) {
                  $this->_options[$k] = $v;
              }
          }
  
          return true;
      }
docs: Set default options.
  
  @return [[@doctodo return_type:setDefaultOptions]] [[@doctodo return_description:setDefaultOptions]]