code: public static function random(
          $length         = 8,
          $allowedChars   = 'abcdefghjkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXY346789'
      ) {
          $return     = '';
          $hashLength = strlen($allowedChars) - 1;
  
          for (;$length > 0; --$length) {
              $return .= $allowedChars{rand(0, $hashLength)};
          }
  
          return str_shuffle($return);
      }
docs: Returns a random string with the given length and given string of
  allowed characters.
  
  @param int $length The length of the random string
  @param string $allowedChars Allowed chars
  @return string