      "* Is this a singly or doubly linked list?\n",
      "    * Singly\n",
      "* Can you insert None values in the list?\n",
      "    * No\n",
      "* Can you use additional data structures?\n",
      "    * Implement both solutions\n",
      "* Can we assume we already have a linked list class that can be used for this problem?\n",
      "    * Yes"
     ]
    },
    {
 
</s>
      "* Is this a singly or doubly linked list?\n",
      "    * Singly\n",
      "* Can you insert None values in the list?\n",
      "    * No\n",


      "* Can we assume we already have a linked list class that can be used for this problem?\n",
      "    * Yes"
     ]
    },
    {
keep keep keep keep replace replace keep keep keep keep keep
 Polish remove duplicates challenge and solution

Update constraints and algorithm discussion.
linked_lists/remove_duplicates/remove_duplicates_solution.ipynb