diff --git a/Part.3.D.indispensable-illusion.ipynb b/Part.3.D.indispensable-illusion.ipynb
index 274001bc3..0cb4ae436 100644
--- a/Part.3.D.indispensable-illusion.ipynb
+++ b/Part.3.D.indispensable-illusion.ipynb
@@ -294,7 +294,7 @@
     "files.sort()\n",
     "for f in files:\n",
     "    if '.ipynb' in f:\n",
-    "        with open(f, 'r', encoding='UTF-8') as file:\n",
+    "        with open(f, 'r', encoding = 'UTF-8') as file:\n",
     "            str = file.read()\n",
     "            pttn = r'\"# (.*)\"\\n'\n",
     "            r = re.findall(pttn, str)\n",