public function getBindingId($binding_index)
    {
        $binding = $this->getBinding();
        return array_key_exists('bindingId', $binding[$binding_index]) ? $binding[$binding_index]['bindingId'] : null;
    }
public function getBindingId($binding_index)
    {
        $binding = $this->getBinding();
        return array_key_exists('bindingId', $binding[$binding_index]) ? $binding[$binding_index]['bindingId'] : null;
    }
public function getBindingId ( $ binding_index ) { $ binding = $ this -> getBinding ( ) ; return array_key_exists ( 'bindingId' , $ binding [ $ binding_index ] ) ? $ binding [ $ binding_index ] [ 'bindingId' ] : null ; }
The identifier of the bundle created when the order was paid or used for payment.

Is present only if the magazine is allowed to create bundles.

@param $binding_index
@return mixed|null
The identifier of the bundle created when the order was paid or used for payment .