presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/SetOperationNodeTranslator.java/SetOperationNodeTranslator/allocateSymbols
class SetOperationNodeTranslator:    private List<Symbol> allocateSymbols(int count, String nameHint, Type type)
    {
        ImmutableList.Builder<Symbol> symbolsBuilder = ImmutableList.builder();
        for (int i = 0; i < count; i++) {
            symbolsBuilder.add(symbolAllocator.newSymbol(nameHint, type));
        }
        return symbolsBuilder.build();
    }