For fun, add an advanced str example to Part 3

Author: audreyfeldroy

part-3.ipynb

@@ -10,7 +10,7 @@
    "name": "python2"
   },
   "name": "",
-  "signature": "sha256:21fa40ef7368043bdaf558035d71a9c7d07f9c147ef8083eadd7fe8a891b7ca2"
+  "signature": "sha256:b363fd42a98873952aba75206e163d01b139ef9e32ca1075b0d581f04bbf654a"
  },
  "nbformat": 3,
  "nbformat_minor": 0,
@@ -340,7 +340,7 @@
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 23
+     "prompt_number": 30
     },
     {
      "cell_type": "code",
@@ -363,7 +363,185 @@
        ]
       }
      ],
-     "prompt_number": 24
+     "prompt_number": 31
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Exercise: Try to break `happy_birthday()`"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "1) Try calling `happy_birthday()` with other values, such as:\n",
+      "* A really, really, really long name\n",
+      "* Something ridiculous that makes no sense grammatically\n",
+      "* Numbers\n",
+      "* Other Python types, if you know about any other ones\n",
+      "\n",
+      "This is how malicious \"black hat\" hackers think when they try to break into desktop and web applications.\n",
+      "\n",
+      "2) Try adding a bad list item to `names`. Experiment with the position of the bad item."
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example: Better String Formatting"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Rather than using string concatenation, let's use a string formatting operator that doesn't care what type of value it receives."
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "def happy_birthday(name):\n",
+      "    print(\"Happy Birthday, dear {0}!\".format(name))"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 39
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Now, the function can print happy birthday greetings for any value of `name`, even for people with bizarre names like:\n",
+      "* 100\n",
+      "* 3.1415927\n",
+      "* \u01ac\u0335\u032c\u030a (The Artist Formerly Known As Prince)"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "happy_birthday(100)\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Happy Birthday, dear 100!\n"
+       ]
+      }
+     ],
+     "prompt_number": 42
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "happy_birthday(3.1415927)"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Happy Birthday, dear 3.1415927!\n"
+       ]
+      }
+     ],
+     "prompt_number": 43
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "happy_birthday(\"\u01ac\u0335\u032c\u030a\")"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Happy Birthday, dear \u01ac\u0335\u032c\u030a!\n"
+       ]
+      }
+     ],
+     "prompt_number": 41
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "It's better to use `format()` just in case `name` isn't guaranteed to be a string."
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Advanced Exercise: Why not use `str()` like this?"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "def happy_birthday(name):\n",
+      "    print(\"Happy Birthday, dear \" + str(name) + \"!\")"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 47
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Answer: You can, but keep in mind that this only works on Python 3:"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "str(u'\\xff')"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "metadata": {},
+       "output_type": "pyout",
+       "prompt_number": 56,
+       "text": [
+        "'\u00ff'"
+       ]
+      }
+     ],
+     "prompt_number": 56
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Now you have some advanced knowledge about how Python 3 handles Unicode better that Python 2!"
+     ]
     },
     {
      "cell_type": "heading",
@@ -475,7 +653,7 @@
      "level": 2,
      "metadata": {},
      "source": [
-      "What are functions used for?"
+      "Summary: What are functions used for?"
      ]
     },
     {