diff --git a/00_core.ipynb b/00_core.ipynb
index 4d720f5..7bd2b9f 100644
--- a/00_core.ipynb
+++ b/00_core.ipynb
@@ -60,7 +60,7 @@
     "from collections import abc\n",
     "\n",
     "from anthropic import Anthropic\n",
-    "from anthropic.types import Usage, TextBlock\n",
+    "from anthropic.types import Usage, TextBlock, Message\n",
     "from anthropic.types.beta.tools import ToolsBetaMessage, tool_use_block\n",
     "from inspect import Parameter\n",
     "from io import BytesIO\n",
@@ -77,9 +77,19 @@
    "id": "0fff8869",
    "metadata": {},
    "outputs": [],
+   "source": [
+    "#| exports\n",
+    "models = 'claude-3-opus-20240229','claude-3-sonnet-20240229','claude-3-haiku-20240307'"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "3e993496",
+   "metadata": {},
+   "outputs": [],
    "source": [
     "#| export\n",
-    "models = 'claude-3-opus-20240229','claude-3-sonnet-20240229','claude-3-haiku-20240307'\n",
     "empty = Parameter.empty"
    ]
   },
@@ -90,7 +100,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "model = models[1]"
+    "model = models[-1]"
    ]
   },
   {
@@ -101,6 +111,16 @@
     "## Client"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "d7a372d5",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "cli = Anthropic()"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -119,21 +139,52 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "8cfb240d",
+   "id": "edb7312e",
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "{'role': 'user', 'content': \"I'm Jeremy\"}"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
    "source": [
-    "#| exports\n",
-    "def mk_msgs(msgs, **kw):\n",
-    "    \"Helper to set 'assistant' role on alternate messages\"\n",
-    "    if isinstance(msgs,str): msgs=[msgs]\n",
-    "    return [mk_msg(o, ('user','assistant')[i%2], **kw) for i,o in enumerate(msgs)]"
+    "prompt = \"I'm Jeremy\"\n",
+    "m = mk_msg(prompt)\n",
+    "m"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "057917c1",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Message(id='msg_01LzzKUnamfWzMEYfb7Lcfxu', content=[TextBlock(text=\"It's nice to meet you Jeremy! As an AI assistant, I don't have a personal identity, but I'm happy to chat and try my best to help you with any questions or tasks you may have. Please feel free to ask me anything.\", type='text')], model='claude-3-haiku-20240307', role='assistant', stop_reason='end_turn', stop_sequence=None, type='message', usage=Usage(input_tokens=10, output_tokens=54))"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "r = cli.messages.create(messages=[m], model=model, max_tokens=100)\n",
+    "r"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "6260b8ba",
+   "id": "544b1326",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -146,7 +197,28 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "660fbb78",
+   "id": "73e42331",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "TextBlock(text=\"It's nice to meet you Jeremy! As an AI assistant, I don't have a personal identity, but I'm happy to chat and try my best to help you with any questions or tasks you may have. Please feel free to ask me anything.\", type='text')"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "find_block(r)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "ca5dea18",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -159,96 +231,124 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "a38a4733",
+   "id": "e9d8bb16",
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "\"It's nice to meet you Jeremy! As an AI assistant, I don't have a personal identity, but I'm happy to chat and try my best to help you with any questions or tasks you may have. Please feel free to ask me anything.\""
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
    "source": [
-    "cli = Anthropic()"
+    "contents(r)"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "fcd9de2e",
+   "id": "8cfb240d",
    "metadata": {},
    "outputs": [],
    "source": [
-    "#|export\n",
-    "@patch\n",
-    "def __add__(self:Usage, b):\n",
-    "    return Usage(input_tokens=self.input_tokens+b.input_tokens, output_tokens=self.output_tokens+b.output_tokens)\n",
-    "\n",
-    "@patch(as_prop=True)\n",
-    "def total(self:Usage): return self.input_tokens+self.output_tokens"
+    "#| exports\n",
+    "def mk_msgs(msgs, **kw):\n",
+    "    \"Helper to set 'assistant' role on alternate messages\"\n",
+    "    if isinstance(msgs,str): msgs=[msgs]\n",
+    "    return [mk_msg(o, ('user','assistant')[i%2], **kw) for i,o in enumerate(msgs)]"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "47d694ab",
+   "id": "1e8f3beb",
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "[{'role': 'user', 'content': \"I'm Jeremy\"},\n",
+       " {'role': 'assistant',\n",
+       "  'content': [TextBlock(text=\"It's nice to meet you Jeremy! As an AI assistant, I don't have a personal identity, but I'm happy to chat and try my best to help you with any questions or tasks you may have. Please feel free to ask me anything.\", type='text')]},\n",
+       " {'role': 'user', 'content': 'I forgot my name. Can you remind me please?'}]"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
    "source": [
-    "@patch\n",
-    "def __repr__(self:Usage): return f'In: {self.input_tokens}; Out: {self.output_tokens}; Total: {self.total}'\n",
-    "\n",
-    "@patch\n",
-    "def _repr_html_(self:ToolsBetaMessage):\n",
-    "    det = '</li>\\n<li>'.join(f'{k}: {v}' for k,v in self.dict().items())\n",
-    "    return f\"\"\"{contents(self)}\n",
-    "<details><ul><li>\n",
-    "{det}\n",
-    "</ul></li></details>\"\"\""
+    "msgs = mk_msgs([prompt, r, 'I forgot my name. Can you remind me please?'])\n",
+    "msgs"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "01186452",
+   "id": "d3b33c41",
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Message(id='msg_01FidCYYvZsh8scXhxK7JiYR', content=[TextBlock(text=\"I'm afraid I don't actually know your name - you introduced yourself to me as Jeremy, but if you've forgotten your own name, I don't have a way to remind you of it. As an AI, I don't have personal information about you stored. I can only respond based on what you tell me directly in our conversation.\", type='text')], model='claude-3-haiku-20240307', role='assistant', stop_reason='end_turn', stop_sequence=None, type='message', usage=Usage(input_tokens=78, output_tokens=72))"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
    "source": [
-    "#| exports\n",
-    "class Client:\n",
-    "    def __init__(self, model, cli=None):\n",
-    "        \"Basic Anthropic messages client\"\n",
-    "        self.model,self.use = model,Usage(input_tokens=0,output_tokens=0)\n",
-    "        self.c = (cli or Anthropic())"
+    "r = cli.messages.create(messages=msgs, model=model, max_tokens=200)\n",
+    "r"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "950f4e5d",
+   "id": "9fecbf43",
    "metadata": {},
    "outputs": [],
    "source": [
-    "c = Client(models[-1])"
+    "@patch\n",
+    "def _repr_html_(self:(ToolsBetaMessage,Message)):\n",
+    "    det = '</li>\\n<li>'.join(f'{k}: {v}' for k,v in self.dict().items())\n",
+    "    return f\"\"\"{contents(self)}\n",
+    "<details><ul><li>\n",
+    "{det}\n",
+    "</ul></li></details>\"\"\""
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "0d027017",
+   "id": "c6f7c428",
    "metadata": {},
    "outputs": [
     {
      "data": {
       "text/html": [
-       "Hello! How can I assist you today?\n",
+       "I'm afraid I don't actually know your name - you introduced yourself to me as Jeremy, but if you've forgotten your own name, I don't have a way to remind you of it. As an AI, I don't have personal information about you stored. I can only respond based on what you tell me directly in our conversation.\n",
        "<details><ul><li>\n",
-       "id: msg_018oPRxexjQpNTZYJG8mBzRm</li>\n",
-       "<li>content: [{'text': 'Hello! How can I assist you today?', 'type': 'text'}]</li>\n",
+       "id: msg_01FidCYYvZsh8scXhxK7JiYR</li>\n",
+       "<li>content: [{'text': \"I'm afraid I don't actually know your name - you introduced yourself to me as Jeremy, but if you've forgotten your own name, I don't have a way to remind you of it. As an AI, I don't have personal information about you stored. I can only respond based on what you tell me directly in our conversation.\", 'type': 'text'}]</li>\n",
        "<li>model: claude-3-haiku-20240307</li>\n",
        "<li>role: assistant</li>\n",
        "<li>stop_reason: end_turn</li>\n",
        "<li>stop_sequence: None</li>\n",
        "<li>type: message</li>\n",
-       "<li>usage: {'input_tokens': 8, 'output_tokens': 12}\n",
+       "<li>usage: {'input_tokens': 78, 'output_tokens': 72}\n",
        "</ul></li></details>"
       ],
       "text/plain": [
-       "ToolsBetaMessage(id='msg_018oPRxexjQpNTZYJG8mBzRm', content=[TextBlock(text='Hello! How can I assist you today?', type='text')], model='claude-3-haiku-20240307', role='assistant', stop_reason='end_turn', stop_sequence=None, type='message', usage=In: 8; Out: 12; Total: 20)"
+       "Message(id='msg_01FidCYYvZsh8scXhxK7JiYR', content=[TextBlock(text=\"I'm afraid I don't actually know your name - you introduced yourself to me as Jeremy, but if you've forgotten your own name, I don't have a way to remind you of it. As an AI, I don't have personal information about you stored. I can only respond based on what you tell me directly in our conversation.\", type='text')], model='claude-3-haiku-20240307', role='assistant', stop_reason='end_turn', stop_sequence=None, type='message', usage=Usage(input_tokens=78, output_tokens=72))"
       ]
      },
      "execution_count": null,
@@ -257,14 +357,205 @@
     }
    ],
    "source": [
-    "a = c.c.beta.tools.messages.create(model=c.model, messages=mk_msgs('Hi'), max_tokens=100)\n",
-    "a"
+    "r"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "a5870416",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Usage(input_tokens=78, output_tokens=72)"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "r.usage"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "47007768",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#| exports\n",
+    "def usage(inp=0, out=0):\n",
+    "    \"Slightly more concise version of `Usage`\"\n",
+    "    return Usage(input_tokens=inp, output_tokens=out)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "04b88b6a",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Usage(input_tokens=5, output_tokens=0)"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "usage(5)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "22dc3680",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#| exports\n",
+    "@patch(as_prop=True)\n",
+    "def total(self:Usage): return self.input_tokens+self.output_tokens"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "6120e315",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "6"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "usage(5,1).total"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "6473320f",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#| exports\n",
+    "@patch\n",
+    "def __repr__(self:Usage): return f'In: {self.input_tokens}; Out: {self.output_tokens}; Total: {self.total}'"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "3339d94e",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "In: 78; Out: 72; Total: 150"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "r.usage"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "ea0bf9a5",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#| exports\n",
+    "@patch\n",
+    "def __add__(self:Usage, b):\n",
+    "    return usage(self.input_tokens+b.input_tokens, self.output_tokens+b.output_tokens)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "47864e07",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "In: 156; Out: 144; Total: 300"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "r.usage+r.usage"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "e757c12c",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#| exports\n",
+    "class Client:\n",
+    "    def __init__(self, model, cli=None):\n",
+    "        \"Basic Anthropic messages client\"\n",
+    "        self.model,self.use = model,Usage(input_tokens=0,output_tokens=0)\n",
+    "        self.c = (cli or Anthropic())"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "193ca8fa",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "In: 0; Out: 0; Total: 0"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "c = Client(model)\n",
+    "c.use"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "65e3488c",
+   "id": "09a2c487",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -280,13 +571,13 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "a9e6201c",
+   "id": "768f91ab",
    "metadata": {},
    "outputs": [
     {
      "data": {
       "text/plain": [
-       "In: 8; Out: 12; Total: 20"
+       "In: 78; Out: 72; Total: 150"
       ]
      },
      "execution_count": null,
@@ -295,14 +586,14 @@
     }
    ],
    "source": [
-    "c._r(a)\n",
+    "c._r(r)\n",
     "c.use"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "2727fdbd",
+   "id": "3ecaa024",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -318,7 +609,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "ea76ae84",
+   "id": "9e3655e8",
    "metadata": {},
    "outputs": [
     {
@@ -352,7 +643,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "ef039c26",
+   "id": "1cf22e90",
    "metadata": {},
    "outputs": [
     {
@@ -437,7 +728,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "2b76b837",
+   "id": "d61b4419",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -452,7 +743,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "3fc55ebe",
+   "id": "8b967131",
    "metadata": {},
    "outputs": [
     {
@@ -473,7 +764,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "5761d788",
+   "id": "de6874d6",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -493,7 +784,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "4cb8cd92",
+   "id": "e1223493",
    "metadata": {},
    "outputs": [
     {
@@ -534,7 +825,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "edc3217b",
+   "id": "1e18ba87",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -551,7 +842,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "19f8273e",
+   "id": "f6cb0cac",
    "metadata": {},
    "outputs": [
     {
@@ -689,7 +980,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "8de0b2ee",
+   "id": "db1ba49e",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -702,7 +993,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "4e936629",
+   "id": "21cb4247",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -730,7 +1021,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "07c50c88",
+   "id": "1d981fb8",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -773,7 +1064,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "4adfe345",
+   "id": "1a8702f9",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -791,7 +1082,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "961c2299",
+   "id": "56b675e4",
    "metadata": {},
    "outputs": [
     {
@@ -846,7 +1137,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "a5e190b8",
+   "id": "94b4a199",
    "metadata": {},
    "source": [
     "## Chat"
@@ -855,7 +1146,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "025c0546",
+   "id": "d9a03565",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -879,17 +1170,17 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "262cb0a5",
+   "id": "14477abd",
    "metadata": {},
    "outputs": [],
    "source": [
-    "c = Chat(models[-1])"
+    "c = Chat(model)"
    ]
   },
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "c3d6882c",
+   "id": "3923cfd5",
    "metadata": {},
    "outputs": [
     {
@@ -911,7 +1202,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "e05b5baf",
+   "id": "1ea37384",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -923,7 +1214,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "74d82105",
+   "id": "6252d3d2",
    "metadata": {},
    "outputs": [
     {
@@ -958,7 +1249,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "7a045192",
+   "id": "a07999da",
    "metadata": {},
    "outputs": [
     {