presto-main/src/main/java/io/prestosql/sql/gen/LambdaExpressionExtractor.java/Visitor/visitSpecialForm
class Visitor:        @Override
        public Void visitSpecialForm(SpecialForm specialForm, Context context)
        {
            for (RowExpression rowExpression : specialForm.getArguments()) {
                rowExpression.accept(this, context);
            }

            return null;
        }