Spot\Query::escapeIdentifier PHP Method

    public function escapeIdentifier($identifier)
    {
        if (is_array($identifier)) {
            array_walk($identifier, function (&$identifier) {
                $identifier = $this->escapeIdentifier($identifier);
            });
            return $identifier;
        }
        if ($this->_noQuote || $identifier === self::ALL_FIELDS) {
            return $identifier;
        }
        if (strpos($identifier, ' ') !== false || strpos($identifier, '(') !== false) {
            return $identifier;
            // complex expression, ain't quote it, do it manually!
        }
        return $this->mapper()->connection()->quoteIdentifier(trim($identifier));
    }