function look_up_language() {


        // Language recognition (STELLA_CURRENT_LANG) for multisite should be in sunrise.php
        if( is_multisite() )
            return;

        $use_lang = $this->langs['default']['prefix'];

        // Language recognition in rewrite_url function. only for subfolder situation
        if( $this->is_subfolder() && is_permalinks_enabled() ){
            $this->set_current_language($use_lang);
            return;
        }

        if ( $this->use_hosts  ):
            foreach ( $this->langs['others'] as $prefix => $lang ) {
                if ( $_SERVER['HTTP_HOST'] == $lang['host'] || $_SERVER['HTTP_HOST'] == 'www.' . $lang['host'] ) {
                    $use_lang = $lang['prefix'];
                    break;
                }
            }
        elseif ( ! is_permalinks_enabled() ) :
            // Non-permalinks variant.
            if ( isset($_GET['lang']) ) :
                foreach ( $this->langs['others'] as $prefix => $lang ) {
                    if ( $_GET['lang'] == $lang['prefix'] ) {
                        $use_lang = $lang['prefix'];

                        break;
                    }
                }
            endif;
        else: // Permalinks no-hosts variant.
            if( ! $this->is_subfolder() ){ //wp is not in subfolder
                $uri = $_SERVER['REQUEST_URI'];
                $code = substr( $uri, 0, 4 );
                if ( '/' != substr( $code, -1 ) )
                    $code = $code . '/';

                foreach ( $this->langs['others'] as $prefix => $lang ) {
                    if ( ! ( false === strpos( $code, '/' . $lang['prefix'] . '/' ) ) ) {
                        $use_lang = $lang['prefix'];
                        break;
                    }
                }
            }

        endif;

        $this->set_current_language($use_lang);
    }

    /**
     * Sets the current language
     * and also the locale
     * @param string $lang current language
     */
    private function set_current_language($lang){

        if( ! defined( 'STELLA_CURRENT_LANG' ) ) {
            define('STELLA_CURRENT_LANG', $lang);
        }



        add_filter('locale', array(&$this,'stella_setlocale'), 10);

    }

    /**
     * locale hook when load_theme_textdomain is present in functions.php
     *
     *
     * called by locale hook
     */
    public function stella_setlocale( $locale ) {
        //for now we have these
        $locales = array(
            'en' => 'en_US',
            'fr' => 'fr_FR',
            'zh' => 'zh_CN'
        );

        return $locales[STELLA_CURRENT_LANG];
    }