Added missing import of List from typing

ipynb/Life.ipynb

@@ -73,7 +73,7 @@
    "outputs": [],
    "source": [
     "from collections     import Counter\n",
-    "from typing          import Set, Tuple, Dict, Iterator\n",
+    "from typing          import Set, Tuple, Dict, Iterator, List\n",
     "from itertools       import islice\n",
     "from IPython.display import clear_output, display_html\n",
     "from time            import sleep\n",