Neo4j.php
protected function subscribeGraphsystem(): void
    {
        $this->kernel->events()->on('graphsystem.touched',  
            function(array $var) {
                $this->index($var);
            })
            ->on('graphsystem.node_deleted',  
            function(string $id) {
                $this->nodeDeleted($id);
            })
            ->on('graphsystem.edge_deleted',  
            function(string $id) {
                $this->edgeDeleted($id);
            }
        );
    }
protected function subscribeGraphsystem(): void
    {
        $this->kernel->events()->on('graphsystem.touched',  
            function(array $var) {
                $this->index($var);
            })
            ->on('graphsystem.node_deleted',  
            function(string $id) {
                $this->nodeDeleted($id);
            })
            ->on('graphsystem.edge_deleted',  
            function(string $id) {
                $this->edgeDeleted($id);
            }
        );
    }
protected function subscribeGraphsystem ( ) : void { $ this -> kernel -> events ( ) -> on ( 'graphsystem.touched' , function ( array $ var ) { $ this -> index ( $ var ) ; } ) -> on ( 'graphsystem.node_deleted' , function ( string $ id ) { $ this -> nodeDeleted ( $ id ) ; } ) -> on ( 'graphsystem.edge_deleted' , function ( string $ id ) { $ this -> edgeDeleted ( $ id ) ; } ) ; }
Listener for kernel events

Interfaces graphsystem and indexes
in every touch or delete operation.

@return void
Listener for kernel events