diff --git a/03_classification.ipynb b/03_classification.ipynb
index b8f7d75..486fd0c 100644
--- a/03_classification.ipynb
+++ b/03_classification.ipynb
@@ -1953,15 +1953,15 @@
     "SPAM_URL = DOWNLOAD_ROOT + \"20030228_spam.tar.bz2\"\n",
     "SPAM_PATH = os.path.join(\"datasets\", \"spam\")\n",
     "\n",
-    "def fetch_spam_data(spam_url=SPAM_URL, spam_path=SPAM_PATH):\n",
+    "def fetch_spam_data(ham_url=HAM_URL, spam_url=SPAM_URL, spam_path=SPAM_PATH):\n",
     "    if not os.path.isdir(spam_path):\n",
     "        os.makedirs(spam_path)\n",
-    "    for filename, url in ((\"ham.tar.bz2\", HAM_URL), (\"spam.tar.bz2\", SPAM_URL)):\n",
+    "    for filename, url in ((\"ham.tar.bz2\", ham_url), (\"spam.tar.bz2\", spam_url)):\n",
     "        path = os.path.join(spam_path, filename)\n",
     "        if not os.path.isfile(path):\n",
     "            urllib.request.urlretrieve(url, path)\n",
     "        tar_bz2_file = tarfile.open(path)\n",
-    "        tar_bz2_file.extractall(path=SPAM_PATH)\n",
+    "        tar_bz2_file.extractall(path=spam_path)\n",
     "        tar_bz2_file.close()"
    ]
   },
@@ -2392,7 +2392,7 @@
     "                for url in urls:\n",
     "                    text = text.replace(url, \" URL \")\n",
     "            if self.replace_numbers:\n",
-    "                text = re.sub(r'\\d+(?:\\.\\d*(?:[eE]\\d+))?', 'NUMBER', text)\n",
+    "                text = re.sub(r'\\d+(?:\\.\\d*)?(?:[eE][+-]?\\d+)?', 'NUMBER', text)\n",
     "            if self.remove_punctuation:\n",
     "                text = re.sub(r'\\W+', ' ', text, flags=re.M)\n",
     "            word_counts = Counter(text.split())\n",
@@ -2455,7 +2455,6 @@
     "            for word, count in word_count.items():\n",
     "                total_count[word] += min(count, 10)\n",
     "        most_common = total_count.most_common()[:self.vocabulary_size]\n",
-    "        self.most_common_ = most_common\n",
     "        self.vocabulary_ = {word: index + 1 for index, (word, count) in enumerate(most_common)}\n",
     "        return self\n",
     "    def transform(self, X, y=None):\n",