public Tree additiveExpressionDashPro(Tree firstConditionalExpression){
		Tree secondConditionalExpression = null;
		Symbol operator = null;

		if((operator = accept(Symbol.Id.PUNCTUATORS,"(\\+|-)")) != null){
			if((secondConditionalExpression = multiplicativeExpressionPro()) != null){
				firstConditionalExpression =  new BinaryExpression(firstConditionalExpression, 
						operator, secondConditionalExpression);

				if((secondConditionalExpression = additiveExpressionDashPro(firstConditionalExpression)) != null){
					return secondConditionalExpression;
				}

				return firstConditionalExpression;
			}

			return null;
		}

		return null;
	}