Add support for Python 3.8, 3.9 in notebook 4 (#8)

Author: dwhswenson

4_mstis_sampling_tutorial.ipynb

@@ -218,10 +218,17 @@
    "outputs": [],
    "source": [
     "# some aspects of storage depend on Python version\n",
-    "if sys.version_info > (3,):\n",
+    "if sys.version_info < (3,):\n",
+    "    filename = \"./inputs/mstis_bootstrap_py2.nc\"\n",
+    "elif (3, 6) <= sys.version_info < (3, 8):\n",
     "    filename = \"./inputs/mstis_bootstrap_py3.nc\"\n",
+    "elif (3, 8) <= sys.version_info < (3, 10):\n",
+    "    filename = \"./inputs/mstis_bootstrap_py38.nc\"\n",
     "else:\n",
-    "    filename = \"./inputs/mstis_bootstrap_py2.nc\""
+    "    raise RuntimeError(\n",
+    "        \"Uh oh! Looks like we don't have an input file for your Python version: \"\n",
+    "        + \".\".join(str(x) for x in sys.version_info[:3])\n",
+    "    )"
    ]
   },
   {
@@ -606,7 +613,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.7.3"
+   "version": "3.8.10"
   },
   "toc": {
    "base_numbering": 1,