       "text": [
        "Test: Empty list, null node to delete\n",
        "Test: One node\n",
        "Test: Multiple nodes\n",
        "Success: test_delete_node\n"
       ]
      }
     ],
 
</s> remove     "        if self.head is None:\n",
 </s> add     "        if self.head is None or node is None:\n", </s> remove    "display_name": "Python 2",
 </s> add    "display_name": "Python 3", </s> remove         assert_equal(linked_list.get_all_data(), [None])
 </s> add         assert_equal(linked_list.get_all_data(), []) </s> remove     "        assert_equal(linked_list.get_all_data(), [None])\n",
 </s> add     "        assert_equal(linked_list.get_all_data(), [])\n", </s> remove    "version": "3.4.3"
 </s> add    "version": "3.5.0"
      "Test: Multiple nodes, delete last element\n",
       "text": [
        "Test: Empty list, null node to delete\n",
        "Test: One node\n",
        "Test: Multiple nodes\n",
      "Test: Multiple nodes, delete last element\n",
        "Success: test_delete_node\n"
       ]
      }
     ],
keep keep keep add keep keep keep keep
 Polish delete mid node challenge and solution

Update edge cases and tests. 
linked_lists/delete_mid/delete_mid_solution.ipynb