diff --git a/index.ipynb b/index.ipynb
index 821dd5a..73a0b15 100644
--- a/index.ipynb
+++ b/index.ipynb
@@ -32,7 +32,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython2",
-   "version": "2.7.10"
+   "version": "2.7.11"
   }
  },
  "nbformat": 4,
diff --git a/tools_matplotlib.ipynb b/tools_matplotlib.ipynb
index 6d4eec0..419ae37 100644
--- a/tools_matplotlib.ipynb
+++ b/tools_matplotlib.ipynb
@@ -63,7 +63,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 3,
+   "execution_count": 48,
    "metadata": {
     "collapsed": false
    },
@@ -1261,7 +1261,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython2",
-   "version": "2.7.10"
+   "version": "2.7.11"
   }
  },
  "nbformat": 4,
diff --git a/tools_numpy.ipynb b/tools_numpy.ipynb
index a32e6de..0364c03 100644
--- a/tools_numpy.ipynb
+++ b/tools_numpy.ipynb
@@ -377,7 +377,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 19,
+   "execution_count": 154,
    "metadata": {
     "collapsed": false,
     "scrolled": false
@@ -523,8 +523,15 @@
     "f = np.array([[1,2],[1000, 2000]], dtype=np.int32)\n",
     "print(\"Array:\")\n",
     "print(f)\n",
+    "print(\"Buffer type:\")\n",
+    "print(type(f.data))\n",
+    "\n",
+    "if (hasattr(f.data, \"tobytes\")):\n",
+    "    data_bytes = f.data.tobytes() # in python 3, f.data is a memoryview\n",
+    "else:\n",
+    "    data_bytes = memoryview(f.data).tobytes() # in python 2, f.data is a buffer\n",
     "print(\"Raw data:\")\n",
-    "print(f.data.hex())"
+    "print(repr(data_bytes))"
    ]
   },
   {
@@ -2908,7 +2915,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython2",
-   "version": "2.7.10"
+   "version": "2.7.11"
   }
  },
  "nbformat": 4,