code: public function config($subcommand)
      {
          $n = func_num_args();
          $subcommand = strtolower($subcommand);
  
          if ($subcommand === 'get') {
              if ($n !== 2) {
                  throw new InvalidArgumentException('ERR Wrong number of arguments for CONFIG get');
              }
              $pattern = func_get_arg(1);
              $ret = array();
              foreach ($this->getConfig() as $name => $value) {
                  if (fnmatch($pattern, $name)) {
                      $ret []= $name;
                      $ret []= $value;
                  }
              }
              return $ret;
          } elseif ($subcommand === 'set') {
              if ($n !== 3) {
                  throw new InvalidArgumentException('ERR Wrong number of arguments for CONFIG set');
              }
              $this->getConfig()->set(func_get_arg(1), func_get_arg(2));
              return true;
          }
  
          throw new InvalidArgumentException('ERR CONFIG subcommand must be one of GET, SET');
      }
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