Highlight example between for loop and list comprehension

Fixes #17

Author:    Micah Denbraver <[email protected]>

Author: macro1

part-4.ipynb

@@ -111,12 +111,44 @@
      "metadata": {},
      "source": [
       "Note how our list comprehension is written within the brackets: The list we're looping over (my_favorite_numbers) is written at the end whereas the action inside of the for-loop is written first: n * n"
+      "Let's compare the two methods real quick by highlighting the different logical parts."
      ]
     },
     {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
+      "First written as a conventional 'for' loop:\n",
+      "<pre>\n",
+      "<span style=\"background:orange\">squared_numbers</span> = []\n",
+      "<span style=\"background:cyan\">for n in</span> <span style=\"background:yellowgreen\">my_favorite_numbers</span>:\n",
+      "&nbsp;&nbsp;&nbsp;&nbsp;squared_numbers.append(<span style=\"background:pink\">n * n</span>)\n",
+      "</pre>"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "And then written as a list comprehension:\n",
+      "<pre>\n",
+      "<span style=\"background:orange\">squared_numbers</span> = [<span style=\"background:pink\">n * n</span> <span style=\"background:cyan\">for n in</span> <span style=\"background:yellowgreen\">my_favorite_numbers</span>]\n",
+      "</pre>"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Look for the <span style=\"background:orange\">new list</span> being created, the <span style=\"background:cyan\">iteration</span> being done over the <span style=\"background:yellowgreen\">orignal list</span> and the <span style=\"background:pink\">transformation</span> being done on each element. List comprehensions are just a cleaner way of building lists from other iterables."
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "### Improving our work\n",
+      "\n",
       "Let's revisit a problem we've already solved in Danny's lecture on lists:\n",
       "\n",
       "Pick every name from a list that begins with a vowel.\n",