Leafo\ScssPhp\Compiler::normalizeValue PHP Method

    public function normalizeValue($value)
    {
        $value = $this->coerceForExpression($this->reduce($value));
        list($type) = $value;
        switch ($type) {
            case Type::T_LIST:
                $value = $this->extractInterpolation($value);
                if ($value[0] !== Type::T_LIST) {
                    return [Type::T_KEYWORD, $this->compileValue($value)];
                }
                foreach ($value[2] as $key => $item) {
                    $value[2][$key] = $this->normalizeValue($item);
                }
                return $value;
            case Type::T_STRING:
                return [$type, '"', [$this->compileStringContent($value)]];
            case Type::T_NUMBER:
                return $value->normalize();
            case Type::T_INTERPOLATE:
                return [Type::T_KEYWORD, $this->compileValue($value)];
            default:
                return $value;
        }
    }