anchor.diff:                           '((make-term 1 '((make-var 'x 1)))
                              (make-term 1 '((make-var 'y 1)))
                              (make-term 1 nil)))))
  +       ; x + y + 1 == (x + y + 1) - 0
          (assert-equal (make-poly
                          '((make-term 1 '((make-var 'x 1)))
                            (make-term 1 '((make-var 'y 1)))
  
positive.code:                            (make-term 1 '((make-var 'y 1)))
                             (make-term 1 nil)))
                         nil))
         (assert-equal (make-poly
                         '((make-term 2 '((make-var 'x 1)))
                           (make-term 2 '((make-var 'y 1)))
  
negative.code:                            (make-term 1 '((make-var 'y 1)))
                             (make-term 1 nil)))))))
      (test
        test-poly- ; Call poly+ and polynegate
                   ; Exceptional use cases are already covered in
                   ; test-make-poly, test-polynegate and
                   ; test-termreduce
        (; 0 == 0 - 0
         (assert-equal nil
                       (poly- nil nil))
         ; -x - y - 1 == 0 - (x + y + 1)
         (assert-equal (make-poly
                         '((make-term -1 '((make-var 'x 1)))
                           (make-term -1 '((make-var 'y 1)))
  