fix pre_code generation

Author: Sorosliu1029

jupyterlab_leetcode/utils/notebook_generator.py

@@ -134,13 +134,13 @@ def __populate_code(self, q):
 
         types = self.__extract_type(snippet)
         typing_import = f"from typing import {', '.join(set(types))}" if types else None
-        source = ["\n\n".join(filter(None, [typing_import, pre_solution.strip(" \n")]))]
+        source = "\n\n".join(filter(None, [typing_import, pre_solution.strip(" \n")]))
         if source:
             pre_code_cell = first(
                 self.template["cells"], lambda c: c["metadata"]["id"] == "pre_code"
             )
             if pre_code_cell:
-                pre_code_cell["source"] = source
+                pre_code_cell["source"] = [source]
             else:
                 code_cell_index = first(
                     enumerate(self.template["cells"]),
@@ -154,7 +154,7 @@ def __populate_code(self, q):
                             "execution_count": None,
                             "metadata": {"id": "pre_code"},
                             "outputs": [],
-                            "source": source,
+                            "source": [source],
                         },
                     )
 

package.json

@@ -1,6 +1,6 @@
 {
     "name": "jupyterlab-leetcode",
-    "version": "0.2.0",
+    "version": "0.2.1",
     "description": "Integrate LeetCode into beloved Jupyter.",
     "keywords": [
         "jupyter",