presto-main/src/main/java/io/prestosql/sql/planner/QueryPlanner.java/QueryPlanner/computeOutputs
class QueryPlanner:    private static List<Symbol> computeOutputs(PlanBuilder builder, List<Expression> outputExpressions)
    {
        ImmutableList.Builder<Symbol> outputSymbols = ImmutableList.builder();
        for (Expression expression : outputExpressions) {
            outputSymbols.add(builder.translate(expression));
        }
        return outputSymbols.build();
    }