diff --git a/examples/Chapter6.ipynb b/examples/Chapter6.ipynb
index efa091b..a812644 100644
--- a/examples/Chapter6.ipynb
+++ b/examples/Chapter6.ipynb
@@ -134,12 +134,13 @@
     "   (change-chcm-to-algb  \n",
     "      chcm\n",
     "      :intr-aprd #'(lambda (degr tnpr)\n",
-    "                      (with-tnpr (degr1 gnrt1 degr2 gnrt2) tnpr\n",
-    "                          (if (zerop degr1) \n",
-    "                              (cmbn degr2 1 gnrt2)\n",
-    "                              (if (zerop degr2)\n",
-    "                                  (cmbn degr1 1 gnrt1)\n",
-    "                                  (zero-cmbn (+ degr1 degr2))))))\n",
+    "                           (declare (ignore degr))\n",
+    "                           (with-tnpr (degr1 gnrt1 degr2 gnrt2) tnpr\n",
+    "                               (if (zerop degr1)\n",
+    "                                   (cmbn degr2 1 gnrt2)\n",
+    "                                   (if (zerop degr2)\n",
+    "                                       (cmbn degr1 1 gnrt1)\n",
+    "                                       (zero-cmbn (+ degr1 degr2))))))\n",
     "      :aprd-strt :gnrt\n",
     "      :orgn `(trivial-algebra ,chcm)))"
    ]