docs: __start__/__end__ consistency (#1874)

* changes

* skip mermaid

* retries fix

* viz error

* changes

docs/docs/tutorials/lats/lats.ipynb

@@ -655,7 +655,7 @@
     "from langgraph.graph import END, StateGraph, START\n",
     "\n",
     "\n",
-    "def should_loop(state: TreeState) -> Literal[\"expand\", \"__end__\"]:\n",
+    "def should_loop(state: TreeState):\n",
     "    \"\"\"Determine whether to continue the tree search.\"\"\"\n",
     "    root = state[\"root\"]\n",
     "    if root.is_solved:\n",
@@ -675,11 +675,13 @@
     "    \"start\",\n",
     "    # Either expand/rollout or finish\n",
     "    should_loop,\n",
+    "    ['expand',END]\n",
     ")\n",
     "builder.add_conditional_edges(\n",
     "    \"expand\",\n",
     "    # Either continue to rollout or finish\n",
     "    should_loop,\n",
+    "    ['expand',END]\n",
     ")\n",
     "\n",
     "graph = builder.compile()"