presto-main/src/main/java/io/prestosql/sql/relational/SqlToRowExpressionTranslator.java/Visitor/visitArithmeticUnary
class Visitor:        @Override
        protected RowExpression visitArithmeticUnary(ArithmeticUnaryExpression node, Void context)
        {
            RowExpression expression = process(node.getValue(), context);

            switch (node.getSign()) {
                case PLUS:
                    return expression;
                case MINUS:
                    return call(
                            metadata.resolveOperator(NEGATION, ImmutableList.of(expression.getType())),
                            getType(node),
                            expression);
            }

            throw new UnsupportedOperationException("Unsupported unary operator: " + node.getSign());
        }