public function tag($id, $tag)
    {
        if ( ! isset($this->serviceTags[$id])) {
            $this->serviceTags[$id] = [];
        }

        $this->serviceTags[$id][] = $tag;
        return $this;
    }
public function tag($id, $tag)
    {
        if ( ! isset($this->serviceTags[$id])) {
            $this->serviceTags[$id] = [];
        }

        $this->serviceTags[$id][] = $tag;
        return $this;
    }
public function tag ( $ id , $ tag ) { if ( ! isset ( $ this -> serviceTags [ $ id ] ) ) { $ this -> serviceTags [ $ id ] = [ ] ; } $ this -> serviceTags [ $ id ] [ ] = $ tag ; return $ this ; }
Tag a service

@param string $id
@param string $tag
@return $this
Tag a service