presto-parser/src/main/java/io/prestosql/sql/tree/DefaultTraversalVisitor.java/DefaultTraversalVisitor/visitFunctionCall
class DefaultTraversalVisitor:    @Override
    protected R visitFunctionCall(FunctionCall node, C context)
    {
        for (Expression argument : node.getArguments()) {
            process(argument, context);
        }

        if (node.getOrderBy().isPresent()) {
            process(node.getOrderBy().get(), context);
        }

        if (node.getWindow().isPresent()) {
            process(node.getWindow().get(), context);
        }

        if (node.getFilter().isPresent()) {
            process(node.getFilter().get(), context);
        }

        return null;
    }