add: local seed with example in initial workflow

Author: BeaMarton13

doc/source/community_detection_guide/notebooks/functions.ipynb

@@ -16,9 +16,30 @@
    "outputs": [],
    "source": [
     "import igraph as ig\n",
+    "import random\n",
+    "from contextlib import contextmanager\n",
     "ig.config[\"plotting.backend\"] = \"matplotlib\""
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "d2d768d4-a5d4-4c72-b044-25ea095a7c0d",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "@contextmanager\n",
+    "def local_random(seed=None):\n",
+    "    \"\"\"Temporarily set the random state, restoring it afterwards.\"\"\"\n",
+    "    state = random.getstate()\n",
+    "    if seed is not None:\n",
+    "        random.seed(seed)\n",
+    "    try:\n",
+    "        yield\n",
+    "    finally:\n",
+    "        random.setstate(state)"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 2,