diff --git a/ch02/05_bpe-from-scratch/bpe-from-scratch.ipynb b/ch02/05_bpe-from-scratch/bpe-from-scratch.ipynb
index 2e8981d..18d3d91 100644
--- a/ch02/05_bpe-from-scratch/bpe-from-scratch.ipynb
+++ b/ch02/05_bpe-from-scratch/bpe-from-scratch.ipynb
@@ -513,43 +513,71 @@
     "                    else:\n",
     "                        print(f\"Skipping pair {pair} as one token is not in the vocabulary.\")\n",
     "\n",
-    "    def encode(self, text):\n",
+    "    def encode(self, text, allowed_special=None):\n",
     "        \"\"\"\n",
-    "        Encode the input text into a list of token IDs.\n",
-    "\n",
+    "        Encode the input text into a list of token IDs, with tiktoken-style handling of special tokens.\n",
+    "    \n",
     "        Args:\n",
-    "            text (str): The text to encode.\n",
-    "\n",
+    "            text (str): The input text to encode.\n",
+    "            allowed_special (set or None): Special tokens to allow passthrough. If None, special handling is disabled.\n",
+    "    \n",
     "        Returns:\n",
-    "            List[int]: The list of token IDs.\n",
+    "            List of token IDs.\n",
     "        \"\"\"\n",
+    "        import re\n",
+    "    \n",
+    "        token_ids = []\n",
+    "    \n",
+    "        # If special token handling is enabled\n",
+    "        if allowed_special is not None and len(allowed_special) > 0:\n",
+    "            # Build regex to match allowed special tokens\n",
+    "            special_pattern = (\n",
+    "                \"(\" + \"|\".join(re.escape(tok) for tok in sorted(allowed_special, key=len, reverse=True)) + \")\"\n",
+    "            )\n",
+    "    \n",
+    "            last_index = 0\n",
+    "            for match in re.finditer(special_pattern, text):\n",
+    "                prefix = text[last_index:match.start()]\n",
+    "                token_ids.extend(self.encode(prefix, allowed_special=None))  # Encode prefix without special handling\n",
+    "    \n",
+    "                special_token = match.group(0)\n",
+    "                if special_token in self.inverse_vocab:\n",
+    "                    token_ids.append(self.inverse_vocab[special_token])\n",
+    "                else:\n",
+    "                    raise ValueError(f\"Special token {special_token} not found in vocabulary.\")\n",
+    "                last_index = match.end()\n",
+    "    \n",
+    "            text = text[last_index:]  # Remaining part to process normally\n",
+    "    \n",
+    "            # Check if any disallowed special tokens are in the remainder\n",
+    "            disallowed = [\n",
+    "                tok for tok in self.inverse_vocab\n",
+    "                if tok.startswith(\"<|\") and tok.endswith(\"|>\") and tok in text and tok not in allowed_special\n",
+    "            ]\n",
+    "            if disallowed:\n",
+    "                raise ValueError(f\"Disallowed special tokens encountered in text: {disallowed}\")\n",
+    "    \n",
+    "        # If no special tokens, or remaining text after special token split:\n",
     "        tokens = []\n",
-    "        # First split on newlines to preserve them\n",
     "        lines = text.split(\"\\n\")\n",
     "        for i, line in enumerate(lines):\n",
     "            if i > 0:\n",
-    "                tokens.append(\"\\n\")  # Add newline token separately\n",
+    "                tokens.append(\"\\n\")\n",
     "            words = line.split()\n",
     "            for j, word in enumerate(words):\n",
-    "                if j == 0:\n",
-    "                    if i > 0:  # Start of a new line but not the first line\n",
-    "                        tokens.append(\"Ġ\" + word)  # Ensure it's marked as a new segment\n",
-    "                    else:\n",
-    "                        tokens.append(word)\n",
-    "                else:\n",
-    "                    # Prefix words in the middle of a line with \"Ġ\"\n",
+    "                if j == 0 and i > 0:\n",
     "                    tokens.append(\"Ġ\" + word)\n",
-    "\n",
-    "        token_ids = []\n",
+    "                elif j == 0:\n",
+    "                    tokens.append(word)\n",
+    "                else:\n",
+    "                    tokens.append(\"Ġ\" + word)\n",
+    "    \n",
     "        for token in tokens:\n",
     "            if token in self.inverse_vocab:\n",
-    "                # token is contained in the vocabulary as is\n",
     "                token_ids.append(self.inverse_vocab[token])\n",
     "            else:\n",
-    "                # Attempt to handle subword tokenization via BPE\n",
-    "                sub_token_ids = self.tokenize_with_bpe(token)\n",
-    "                token_ids.extend(sub_token_ids)\n",
-    "\n",
+    "                token_ids.extend(self.tokenize_with_bpe(token))\n",
+    "    \n",
     "        return token_ids\n",
     "\n",
     "    def tokenize_with_bpe(self, token):\n",
@@ -781,7 +809,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 25,
+   "execution_count": 5,
    "id": "51872c08-e01b-40c3-a8a0-e8d6a773e3df",
    "metadata": {},
    "outputs": [
@@ -940,6 +968,46 @@
   {
    "cell_type": "code",
    "execution_count": 10,
+   "id": "78249752-38d7-47b9-b259-912bcc093dc4",
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "[424, 256, 654, 531, 302, 311, 256, 296, 97, 465, 121, 595, 841, 116, 287, 466, 256, 326, 972, 46, 256, 60, 124, 271, 683, 102, 116, 461, 116, 124, 62]\n"
+     ]
+    }
+   ],
+   "source": [
+    "input_text = \"Jack embraced beauty through art and life. <|endoftext|> \"\n",
+    "token_ids = tokenizer.encode(input_text)\n",
+    "print(token_ids)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 11,
+   "id": "0331d37d-49a3-44f7-9aa9-9834e0938741",
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "[424, 256, 654, 531, 302, 311, 256, 296, 97, 465, 121, 595, 841, 116, 287, 466, 256, 326, 972, 46, 257]\n"
+     ]
+    }
+   ],
+   "source": [
+    "input_text = \"Jack embraced beauty through art and life. <|endoftext|> \"\n",
+    "token_ids = tokenizer.encode(input_text, allowed_special={\"<|endoftext|>\"})\n",
+    "print(token_ids)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
    "id": "1ed1b344-f7d4-4e9e-ac34-2a04b5c5b7a8",
    "metadata": {},
    "outputs": [
@@ -947,8 +1015,8 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "Number of characters: 42\n",
-      "Number of token IDs: 20\n"
+      "Number of characters: 57\n",
+      "Number of token IDs: 21\n"
      ]
     }
    ],
@@ -975,7 +1043,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 11,
+   "execution_count": 13,
    "id": "da0e1faf-1933-43d9-b681-916c282a8f86",
    "metadata": {},
    "outputs": [
@@ -983,7 +1051,7 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "[424, 256, 654, 531, 302, 311, 256, 296, 97, 465, 121, 595, 841, 116, 287, 466, 256, 326, 972, 46]\n"
+      "[424, 256, 654, 531, 302, 311, 256, 296, 97, 465, 121, 595, 841, 116, 287, 466, 256, 326, 972, 46, 257]\n"
      ]
     }
    ],
@@ -993,7 +1061,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 12,
+   "execution_count": 14,
    "id": "8b690e83-5d6b-409a-804e-321c287c24a4",
    "metadata": {},
    "outputs": [
@@ -1001,7 +1069,7 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "Jack embraced beauty through art and life.\n"
+      "Jack embraced beauty through art and life.<|endoftext|>\n"
      ]
     }
    ],
@@ -1019,7 +1087,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 13,
+   "execution_count": 15,
    "id": "2b9e6289-92cb-4d88-b3c8-e836d7c8095f",
    "metadata": {},
    "outputs": [
@@ -1046,7 +1114,8 @@
       "256 ->  \n",
       "326 -> li\n",
       "972 -> fe\n",
-      "46 -> .\n"
+      "46 -> .\n",
+      "257 -> <|endoftext|>\n"
      ]
     }
    ],
@@ -1073,7 +1142,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 14,
+   "execution_count": 16,
    "id": "c7056cb1-a9a3-4cf6-8364-29fb493ae240",
    "metadata": {},
    "outputs": [
@@ -1083,7 +1152,7 @@
        "'This is some text.'"
       ]
      },
-     "execution_count": 14,
+     "execution_count": 16,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1096,7 +1165,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 15,
+   "execution_count": 17,
    "id": "37bc6753-8f35-4ec7-b23e-df4a12103cb4",
    "metadata": {},
    "outputs": [
@@ -1106,7 +1175,7 @@
        "'This is some text with \\n newline characters.'"
       ]
      },
-     "execution_count": 15,
+     "execution_count": 17,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1135,7 +1204,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 16,
+   "execution_count": 18,
    "id": "955181cb-0910-4c6a-9c22-d8292a3ec1fc",
    "metadata": {},
    "outputs": [],
@@ -1146,7 +1215,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 17,
+   "execution_count": 19,
    "id": "6e5ccfe7-ac67-42f3-b727-87886a8867f1",
    "metadata": {},
    "outputs": [],
@@ -1166,7 +1235,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 18,
+   "execution_count": 20,
    "id": "00d9bf8f-756f-48bf-81b8-b890e2c2ef13",
    "metadata": {},
    "outputs": [
@@ -1174,7 +1243,7 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "Jack embraced beauty through art and life.\n"
+      "Jack embraced beauty through art and life.<|endoftext|>\n"
      ]
     }
    ],
@@ -1184,7 +1253,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 19,
+   "execution_count": 21,
    "id": "e7addb64-2892-4e1c-85dd-4f5152740099",
    "metadata": {},
    "outputs": [
@@ -1194,7 +1263,7 @@
        "'This is some text with \\n newline characters.'"
       ]
      },
-     "execution_count": 19,
+     "execution_count": 21,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1224,7 +1293,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 20,
+   "execution_count": 22,
    "id": "b45b4366-2c2b-4309-9a14-febf3add8512",
    "metadata": {},
    "outputs": [
@@ -1264,7 +1333,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 21,
+   "execution_count": 23,
    "id": "74306e6c-47d3-45a3-9e0f-93f7303ef601",
    "metadata": {},
    "outputs": [],
@@ -1285,7 +1354,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 22,
+   "execution_count": 24,
    "id": "2bb722b4-dbf5-4a0c-9120-efda3293f132",
    "metadata": {},
    "outputs": [
@@ -1295,7 +1364,7 @@
        "50257"
       ]
      },
-     "execution_count": 22,
+     "execution_count": 24,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1314,7 +1383,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 23,
+   "execution_count": 25,
    "id": "e4866de7-fb32-4dd6-a878-469ec734641c",
    "metadata": {},
    "outputs": [
@@ -1334,7 +1403,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 24,
+   "execution_count": 26,
    "id": "3da8d9b2-af55-4b09-95d7-fabd983e919e",
    "metadata": {},
    "outputs": [