public function generate($command){
    $perl_cmd = str_replace('_', '-', $command);
    if ( isset($this->commands[$perl_cmd]) ){
      $cmd = $this->commands[$perl_cmd];
      $st = '$vm->'.$command.'(['.PHP_EOL;
      foreach ( $cmd['args'] as $k => $v ){
        $st .= "'$k' => ".($v['binary'] ? '0' : "''").PHP_EOL;
      }
      $st .= ']);';
      return $st;
    }
    return false;
  }