| No ExStr is no more supported. But you can do it your self by calling
| the parser on your string if you really don't want switch to an AST
| based quotation expander.

OK, that's fine. But how do I do that? Concretely, this is what I had
before, so what should I have now?

  Quotation.add "" (Quotation.ExStr (fun x -> quotexpander));;

I don't mind in principle writing an AST-producing expander, but at the
moment the priority is to get my code working in 3.10 with minimal
expenditure of effort.

John.