diff --git a/notebooks/reprojection/reproject_demo.ipynb b/notebooks/reprojection/reproject_demo.ipynb
index 965a638b2..6de5ab2ae 100644
--- a/notebooks/reprojection/reproject_demo.ipynb
+++ b/notebooks/reprojection/reproject_demo.ipynb
@@ -26,32 +26,33 @@
     "import numpy as np\n",
     "from os import path\n",
     "\n",
+    "\n",
     "# visualization utility.\n",
     "def plot_images(obstimes, image1=None, image2=None, image3=None, image4=None):\n",
-    "    '''Plot four images side by side'''\n",
-    "    \n",
-    "    min_val = -1.\n",
-    "    fig = plt.figure(figsize=(10,10))\n",
+    "    \"\"\"Plot four images side by side\"\"\"\n",
+    "\n",
+    "    min_val = -1.0\n",
+    "    fig = plt.figure(figsize=(10, 10))\n",
     "    if image1:\n",
-    "        f1 = fig.add_subplot(2,2,1, projection=image1.wcs)\n",
+    "        f1 = fig.add_subplot(2, 2, 1, projection=image1.wcs)\n",
     "        f1.title.set_text(str(obstimes[0]))\n",
-    "        plt.imshow(image1.data, vmin=min_val, origin='lower')\n",
-    "        plt.grid(color='white', ls='solid')\n",
+    "        plt.imshow(image1.data, vmin=min_val, origin=\"lower\")\n",
+    "        plt.grid(color=\"white\", ls=\"solid\")\n",
     "    if image2:\n",
-    "        f2 = fig.add_subplot(2,2,2, projection=image2.wcs)\n",
+    "        f2 = fig.add_subplot(2, 2, 2, projection=image2.wcs)\n",
     "        f2.title.set_text(str(obstimes[1]))\n",
-    "        plt.imshow(image2.data, vmin=min_val, origin='lower')\n",
-    "        plt.grid(color='white', ls='solid')\n",
+    "        plt.imshow(image2.data, vmin=min_val, origin=\"lower\")\n",
+    "        plt.grid(color=\"white\", ls=\"solid\")\n",
     "    if image3:\n",
-    "        f3 = fig.add_subplot(2,2,3, projection=image3.wcs)\n",
+    "        f3 = fig.add_subplot(2, 2, 3, projection=image3.wcs)\n",
     "        f3.title.set_text(str(obstimes[2]))\n",
-    "        plt.imshow(image3.data, vmin=min_val, origin='lower')\n",
-    "        plt.grid(color='white', ls='solid')\n",
+    "        plt.imshow(image3.data, vmin=min_val, origin=\"lower\")\n",
+    "        plt.grid(color=\"white\", ls=\"solid\")\n",
     "    if image4:\n",
-    "        f4 = fig.add_subplot(2,2,4, projection=image4.wcs)\n",
+    "        f4 = fig.add_subplot(2, 2, 4, projection=image4.wcs)\n",
     "        f4.title.set_text(str(obstimes[3]))\n",
-    "        plt.imshow(image4.data, vmin=min_val, origin='lower')\n",
-    "        plt.grid(color='white', ls='solid')"
+    "        plt.imshow(image4.data, vmin=min_val, origin=\"lower\")\n",
+    "        plt.grid(color=\"white\", ls=\"solid\")"
    ]
   },
   {
@@ -76,7 +77,7 @@
     "project_root_dir = path.abspath((path.dirname(path.dirname(path.abspath(\"\")))))\n",
     "fake_data_loc = \"tests/data/shifted_wcs_diff_dimms_tiled.fits\"\n",
     "\n",
-    "wunit = WorkUnit.from_fits(path.join(project_root_dir,fake_data_loc))\n",
+    "wunit = WorkUnit.from_fits(path.join(project_root_dir, fake_data_loc))\n",
     "wunit"
    ]
   },
@@ -199,7 +200,7 @@
     "image2_mask = CCDData(images[2].get_mask().image, unit=\"adu\")\n",
     "image2_mask.wcs = uwunit.wcs\n",
     "\n",
-    "plot_images([uwunit.get_all_obstimes()[-1]]*2, original_image2_mask, image2_mask)"
+    "plot_images([uwunit.get_all_obstimes()[-1]] * 2, original_image2_mask, image2_mask)"
    ]
   },
   {