anchor.diff:                   ; Exceptional use cases are already covered in
                    ; test-make-poly, test-termreduce and
                    ; test-termlist*
  +                 ; (see the implementation of poly*)
         (; 0 == 0 * 0
          (assert-equal nil
                        (poly* nil nil))
  
positive.code:       test-poly+ ; Call termreduce internally
                   ; Exceptional use cases are already covered in
                   ; test-make-poly and test-termreduce
        (; 0 == 0 + 0
         (assert-equal nil
                       (poly+ nil nil))
  
negative.code:                  ; Exceptional use cases are already covered in
                   ; test-make-poly, test-polynegate and
                   ; test-termreduce
                   ; (see the implementation of poly-)
        (; 0 == 0 - 0
         (assert-equal nil
                       (poly- nil nil))
  