public function display_statistics()
 {
     print "Statistics for VSYS '" . $this->name . "'\n";
     print "- " . $this->securityRules->count() . " security rules\n";
     print "- " . $this->natRules->count() . " nat rules\n";
     print "- " . $this->decryptionRules->count() . " decryption rules\n";
     print "- " . $this->addressStore->countAddresses() . " address objects\n";
     print "- " . $this->addressStore->countAddressGroups() . " address groups\n";
     print "- " . $this->serviceStore->countServices() . " service objects\n";
     print "- " . $this->serviceStore->countServiceGroups() . " service groups\n";
     print "- " . $this->addressStore->countTmpAddresses() . " temporary address objects\n";
     print "- " . $this->serviceStore->countTmpServices() . " temporary service objects\n";
     print "- " . $this->tagStore->count() . " tags. " . $this->tagStore->countUnused() . " unused\n";
     print "- " . $this->zoneStore->count() . " zones.\n";
     print "- " . $this->appStore->count() . " apps.\n";
 }