presto-main/src/main/java/io/prestosql/sql/relational/SqlToRowExpressionTranslator.java/Visitor/visitSpecialForm
class Visitor:            @Override
            public RowExpression visitSpecialForm(SpecialForm specialForm, Void context)
            {
                return new SpecialForm(specialForm.getForm(), targetType, specialForm.getArguments());
            }