     "metadata": {},
     "source": [
      "## Constraints\n",
      "\n",
      "* Is this a singly or doubly linked list?\n",
      "    * Singly\n",
      "* Is this a circular list?\n",
      "    * No\n",
      "* Do we keep track of the tail or just the head?\n",
      "    * Just the head\n",
      "* Can we insert None values?\n",
      "    * No"
     ]
 
</s> remove     "* Is this a singly or doubly linked list?\n",
    "    * Singly\n",
    "* Is this a circular list?\n",
    "    * No\n",
 </s> add     "* Can we assume this is a non-circular, singly linked list?\n",
    "    * Yes\n", </s> remove     "* Is this a singly or doubly linked list?\n",
    "    * Singly\n",
 </s> add     "* Can we assume this is a non-circular, singly linked list?\n",
    "    * Yes\n", </s> remove     "* Is this a singly or doubly linked list?\n",
    "    * Singly\n",
 </s> add     "* Can we assume this is a non-circular, singly linked list?\n",
    "    * Yes\n",
    "* Can we assume this is a non-circular, singly linked list?\n",
    "    * Yes\n",
     "metadata": {},
     "source": [
      "## Constraints\n",
      "\n",
    "* Can we assume this is a non-circular, singly linked list?\n",
    "    * Yes\n",
    "* Can we assume this is a non-circular, singly linked list?\n",
    "    * Yes\n",
    "* Can we assume this is a non-circular, singly linked list?\n",
    "    * Yes\n",
    "* Can we assume this is a non-circular, singly linked list?\n",
    "    * Yes\n",
      "* Do we keep track of the tail or just the head?\n",
      "    * Just the head\n",
      "* Can we insert None values?\n",
      "    * No"
     ]
keep keep keep keep replace replace replace replace keep keep keep keep keep
 Update linked list constraints

Specify singly linked list, non circular.  Also specify the solution fits in memory. 
linked_lists/linked_list/linked_list_challenge.ipynb