Add 'task 4' to exercises

Author: ma595

worked-solutions/01_penguin_classification_solutions.ipynb

@@ -196,10 +196,10 @@
     "        # this gives a 'species' i.e. one of ('Gentoo',), ('Chinstrap',), or ('Adelie',)\n",
     "        tgts = tuple(self.split.iloc[idx][self.target_keys])\n",
     "\n",
-    "        # Exercise #1: convert the feats (Series) to PyTorch Tensors\n",
+    "        # Task 4 - Exercise #1: convert the feats (Series) to PyTorch Tensors\n",
     "        feats = tensor(feats, dtype=float32)\n",
     "\n",
-    "        # Exercise #2: convert target to a 'one-hot' vector.\n",
+    "        # Task 4 - Exercise #2: convert target to a 'one-hot' vector.\n",
     "        target_names = sorted(self.full_df.species.unique())\n",
     "        tgts = eye(len(target_names))[target_names.index(tgts[0])]\n",
     "\n",