public function colorScheme($key=null)
    {
        $all = $this->allColorSchemes();
        $allKeys = array_keys($all);
        if (count($allKeys)>0) {
            if ($key && isset($all[strtolower($key)])) {
                return $all[strtolower($key)];
            }    
            return $all[$allKeys[0]];
        }
        return null;
    }