diff --git a/collider/Simulation_interface.ipynb b/collider/Simulation_interface.ipynb
index 2ffe83f..a35ec0c 100644
--- a/collider/Simulation_interface.ipynb
+++ b/collider/Simulation_interface.ipynb
@@ -8,6 +8,16 @@
     "This notebook provides an interface for a toy model of a chemical reaction in the gas phase."
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "a =0\n",
+    "print (a)"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},