diff --git a/extras/__init__.py b/extras/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/extras/scripts/hw_0_helper.py b/extras/scripts/hw_0_helper.py
new file mode 100644
index 00000000..390092d8
--- /dev/null
+++ b/extras/scripts/hw_0_helper.py
@@ -0,0 +1,31 @@
+import ast
+import os
+import pytest
+from .nb_helper import *
+
+
+# https://sadh.life/post/ast/
+class FuncCallChecker(ast.NodeVisitor):
+    def __init__(self, func: str):
+        self.func = func
+        self.num_calls = 0
+
+    def visit_Call(self, node):
+        if isinstance(node.func, ast.Name) and node.func.id == self.func:
+            self.num_calls += 1
+
+
+@pytest.fixture()
+def notebook():
+    nb_full_path = os.path.join(os.getcwd(), "hw_0.ipynb")
+    return read_notebook(nb_full_path)
+
+
+@pytest.fixture()
+def script(notebook):
+    return notebook_to_script(notebook)
+
+
+@pytest.fixture()
+def tree(script):
+    return ast.parse(script)
diff --git a/hw_0.ipynb b/hw_0.ipynb
index 88ca68f2..8c43739a 100644
--- a/hw_0.ipynb
+++ b/hw_0.ipynb
@@ -184,6 +184,76 @@
     "# your code goes here"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Autograding\n",
+    "\n",
+    "Using [this approach](https://stackoverflow.com/a/70920396/358804)."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "scrolled": true
+   },
+   "outputs": [],
+   "source": [
+    "import ipytest\n",
+    "ipytest.autoconfig()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\u001b[31mF\u001b[0m\u001b[31m                                                                                            [100%]\u001b[0m\n",
+      "============================================= FAILURES =============================================\n",
+      "\u001b[31m\u001b[1m_________________________________________ test_num_inputs __________________________________________\u001b[0m\n",
+      "\n",
+      "tree = <ast.Module object at 0x10e7da1a0>\n",
+      "\n",
+      "    \u001b[94mdef\u001b[39;49;00m \u001b[92mtest_num_inputs\u001b[39;49;00m(tree):\n",
+      "        checker = FuncCallChecker(\u001b[33m\"\u001b[39;49;00m\u001b[33minput\u001b[39;49;00m\u001b[33m\"\u001b[39;49;00m)\n",
+      "        checker.visit(tree)\n",
+      "    \n",
+      ">       \u001b[94massert\u001b[39;49;00m checker.num_calls >= \u001b[94m8\u001b[39;49;00m, \u001b[33m\"\u001b[39;49;00m\u001b[33myou don\u001b[39;49;00m\u001b[33m'\u001b[39;49;00m\u001b[33mt have enough calls to input()\u001b[39;49;00m\u001b[33m\"\u001b[39;49;00m\n",
+      "\u001b[1m\u001b[31mE       AssertionError: you don't have enough calls to input()\u001b[0m\n",
+      "\u001b[1m\u001b[31mE       assert 2 >= 8\u001b[0m\n",
+      "\u001b[1m\u001b[31mE        +  where 2 = <extras.scripts.hw_0_helper.FuncCallChecker object at 0x10e7d8df0>.num_calls\u001b[0m\n",
+      "\n",
+      "\u001b[1m\u001b[31m/var/folders/kg/1ys0dccx4237f5wsd_w10dt80000gn/T/ipykernel_68325/4145485001.py\u001b[0m:8: AssertionError\n",
+      "\u001b[33m========================================= warnings summary =========================================\u001b[0m\n",
+      "tmpc439hpt9.py::test_num_inputs\n",
+      "  /usr/local/Caskroom/miniconda/base/envs/python-public-policy/lib/python3.10/site-packages/IPython/core/inputsplitter.py:21: DeprecationWarning: IPython.core.inputsplitter is deprecated since IPython 7 in favor of `IPython.core.inputtransformer2`\n",
+      "    warn('IPython.core.inputsplitter is deprecated since IPython 7 in favor of `IPython.core.inputtransformer2`',\n",
+      "\n",
+      "-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html\n",
+      "===================================== short test summary info ======================================\n",
+      "FAILED tmpc439hpt9.py::test_num_inputs - AssertionError: you don't have enough calls to input()\n"
+     ]
+    }
+   ],
+   "source": [
+    "%%ipytest -qq\n",
+    "\n",
+    "from extras.scripts.hw_0_helper import *\n",
+    "\n",
+    "\n",
+    "def test_num_inputs(tree):\n",
+    "    checker = FuncCallChecker(\"input\")\n",
+    "    checker.visit(tree)\n",
+    "\n",
+    "    assert checker.num_calls >= 8, \"you don't have enough calls to input()\""
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},