PhpMigration\SymbolTable::prepareKey PHP Method

    protected function prepareKey(&$key)
    {
        // Compatible with almost all type key
        if (is_object($key) && method_exists($key, '__toString')) {
            $key = (string) $key;
        }
        if (!is_string($key)) {
            return false;
        }
        $key = $this->caseSensitive ? $key : strtolower($key);
        return true;
    }