src/main/java/com/virgo47/vexpressed/validation/ExpressionValidatorVisitor.java
private ExpressionType commonNumberType(ExpressionType left, ExpressionType right) {
		if (left == INTEGER && right == INTEGER) {
			return INTEGER;
		}
		if (left == DECIMAL && right == DECIMAL
			|| left == INTEGER && right == DECIMAL
			|| left == DECIMAL && right == INTEGER)
		{
			return DECIMAL;
		}

		return null;
	}
/**
	 * Returns common number type promoting from {@link ExpressionType#INTEGER} to
	 * {@link ExpressionType#DECIMAL} as needed. Returns null if both sides are not number.
	 */
Returns common number type promoting from  ExpressionType#INTEGER to
ExpressionType#DECIMAL as needed. Returns null if both sides are not number.
Returns common number type promoting from ExpressionType#INTEGER to ExpressionType#DECIMAL as needed . Returns null if both sides are not number .
private ExpressionType commonNumberType(ExpressionType left, ExpressionType right) {
		if (left == INTEGER && right == INTEGER) {
			return INTEGER;
		}
		if (left == DECIMAL && right == DECIMAL
			|| left == INTEGER && right == DECIMAL
			|| left == DECIMAL && right == INTEGER)
		{
			return DECIMAL;
		}
		return null;
	}
private ExpressionType commonNumberType ( ExpressionType left , ExpressionType right ) { if ( left == INTEGER && right == INTEGER ) { return INTEGER ; } if ( left == DECIMAL && right == DECIMAL || left == INTEGER && right == DECIMAL || left == DECIMAL && right == INTEGER ) { return DECIMAL ; } return null ; }
Returns common number type promoting from {@link ExpressionType#INTEGER} to
 {@link ExpressionType#DECIMAL} as needed.
Returns common number type promoting from { @link ExpressionType#INTEGER } to { @link ExpressionType#DECIMAL } as needed .