presto-main/src/main/java/io/prestosql/sql/planner/SymbolsExtractor.java/SymbolsExtractor/extractAll
class SymbolsExtractor:    public static List<Symbol> extractAll(WindowNode.Function function)
    {
        ImmutableList.Builder<Symbol> builder = ImmutableList.builder();
        for (Expression argument : function.getArguments()) {
            builder.addAll(extractAll(argument));
        }
        function.getFrame().getEndValue().ifPresent(builder::add);
        function.getFrame().getStartValue().ifPresent(builder::add);
        return builder.build();
    }