class Expression {

    public static Expression createExpressionFromDescribedExpression(String describedExpression) {
        if (describedExpression != null) {
            String language = null;
            String expression = describedExpression;
            if (describedExpression.matches("[a-zA-Z0-9]+:.+")) {
                language = describedExpression.substring(0, describedExpression.indexOf(':'));
                expression = describedExpression.substring(describedExpression.indexOf(':') + 1);
            }
            return new Expression(expression, language);
        }

        return null;
    }

    public  Expression(String expression, String language);
    public  Expression(String expression);
    public  Expression(Expression toCopy);

}