anchor.diff:  JSON strings.  Returns ID on success, NIL if there was no such ID
   found."
     (log:debug "Attempt update of ~A" id)
  +  (ensure-model-query model 'insert-old$ 'update$)
     (with-retry-serialization-failure ("update")
       (with-transaction-type (repeatable-read-rw)
         (insert-old$ model id)
  
positive.code: Postgres type *ID-TYPE*) in MODEL, a symbol, and return a parse of the
  JSON string by the the function of one argument designated by
  FROM-JSON.  Make it #'identity to return just the JSON string proper."
    (funcall from-json (with-transaction-type (read-committed-ro)
                         (get$ model id))))
  
  
negative.code: Postgres type *ID-TYPE*).  Returns ID on success, NIL if there was no
  such ID found."
    (log:debug "Attempt delete of ~A" id)
    (ensure-model-query model 'insert-old$ 'delete$)
    (with-retry-serialization-failure ("delete")
      (with-transaction-type (repeatable-read-rw)
        (insert-old$ model id)
  