diff --git a/graphs_trees/graph_bfs/bfs_challenge.ipynb b/graphs_trees/graph_bfs/bfs_challenge.ipynb
index 78fc0cc..0b93740 100644
--- a/graphs_trees/graph_bfs/bfs_challenge.ipynb
+++ b/graphs_trees/graph_bfs/bfs_challenge.ipynb
@@ -37,6 +37,10 @@
     "* Is the graph directed?\n",
     "    * Yes\n",
     "* Can we assume we already have Graph and Node classes?\n",
+    "    * Yes\n",
+    "* Can we assume the inputs are valid?\n",
+    "    * Yes\n",
+    "* Can we assume this fits memory?\n",
     "    * Yes"
    ]
   },
@@ -186,21 +190,21 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 2",
+   "display_name": "Python 3",
    "language": "python",
-   "name": "python2"
+   "name": "python3"
   },
   "language_info": {
    "codemirror_mode": {
     "name": "ipython",
-    "version": 2
+    "version": 3
    },
    "file_extension": ".py",
    "mimetype": "text/x-python",
    "name": "python",
    "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython2",
-   "version": "2.7.10"
+   "pygments_lexer": "ipython3",
+   "version": "3.5.0"
   }
  },
  "nbformat": 4,
diff --git a/graphs_trees/graph_bfs/bfs_solution.ipynb b/graphs_trees/graph_bfs/bfs_solution.ipynb
index 4f1090f..943cdd9 100644
--- a/graphs_trees/graph_bfs/bfs_solution.ipynb
+++ b/graphs_trees/graph_bfs/bfs_solution.ipynb
@@ -36,6 +36,10 @@
     "* Is the graph directed?\n",
     "    * Yes\n",
     "* Can we assume we already have Graph and Node classes?\n",
+    "    * Yes\n",
+    "* Can we assume the inputs are valid?\n",
+    "    * Yes\n",
+    "* Can we assume this fits memory?\n",
     "    * Yes"
    ]
   },
@@ -219,21 +223,21 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 2",
+   "display_name": "Python 3",
    "language": "python",
-   "name": "python2"
+   "name": "python3"
   },
   "language_info": {
    "codemirror_mode": {
     "name": "ipython",
-    "version": 2
+    "version": 3
    },
    "file_extension": ".py",
    "mimetype": "text/x-python",
    "name": "python",
    "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython2",
-   "version": "2.7.10"
+   "pygments_lexer": "ipython3",
+   "version": "3.5.0"
   }
  },
  "nbformat": 4,
diff --git a/graphs_trees/graph_dfs/dfs_challenge.ipynb b/graphs_trees/graph_dfs/dfs_challenge.ipynb
index a8fa189..fb792f7 100644
--- a/graphs_trees/graph_dfs/dfs_challenge.ipynb
+++ b/graphs_trees/graph_dfs/dfs_challenge.ipynb
@@ -37,6 +37,10 @@
     "* Is the graph directed?\n",
     "    * Yes\n",
     "* Can we assume we already have Graph and Node classes?\n",
+    "    * Yes\n",
+    "* Can we assume the inputs are valid?\n",
+    "    * Yes\n",
+    "* Can we assume this fits memory?\n",
     "    * Yes"
    ]
   },
@@ -187,21 +191,21 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 2",
+   "display_name": "Python 3",
    "language": "python",
-   "name": "python2"
+   "name": "python3"
   },
   "language_info": {
    "codemirror_mode": {
     "name": "ipython",
-    "version": 2
+    "version": 3
    },
    "file_extension": ".py",
    "mimetype": "text/x-python",
    "name": "python",
    "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython2",
-   "version": "2.7.10"
+   "pygments_lexer": "ipython3",
+   "version": "3.5.0"
   }
  },
  "nbformat": 4,
diff --git a/graphs_trees/graph_dfs/dfs_solution.ipynb b/graphs_trees/graph_dfs/dfs_solution.ipynb
index 3f50459..f5c8377 100644
--- a/graphs_trees/graph_dfs/dfs_solution.ipynb
+++ b/graphs_trees/graph_dfs/dfs_solution.ipynb
@@ -36,6 +36,10 @@
     "* Is the graph directed?\n",
     "    * Yes\n",
     "* Can we assume we already have Graph and Node classes?\n",
+    "    * Yes\n",
+    "* Can we assume the inputs are valid?\n",
+    "    * Yes\n",
+    "* Can we assume this fits memory?\n",
     "    * Yes"
    ]
   },
@@ -209,21 +213,21 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 2",
+   "display_name": "Python 3",
    "language": "python",
-   "name": "python2"
+   "name": "python3"
   },
   "language_info": {
    "codemirror_mode": {
     "name": "ipython",
-    "version": 2
+    "version": 3
    },
    "file_extension": ".py",
    "mimetype": "text/x-python",
    "name": "python",
    "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython2",
-   "version": "2.7.10"
+   "pygments_lexer": "ipython3",
+   "version": "3.5.0"
   }
  },
  "nbformat": 4,