@Override
    public Expression parseExpression() throws IOException {
        Expression expression = new Expression();
        expression.getTermList().add(parseTerm());
        while (curToken.type == PLUS ||
                curToken.type == MINUS) {
            switch (curToken.type) {
                case PLUS:
                    curToken = lexer.getToken();
                    expression.getOperatios().add(PLUS);
                    expression.getTermList().add(parseTerm());
                    break;
                case MINUS:
                    curToken = lexer.getToken();
                    expression.getOperatios().add(MINUS);
                    expression.getTermList().add(parseTerm());
                    break;
            }
        }

        return expression;
    }