removed solution from fib and removed typo

Author: ptrthegr8

demo_generators.ipynb

@@ -278,7 +278,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Excercise\n",
+    "## Exercise\n",
     "In the previous example, we knew all the student names up front.  Could have just written a for-loop to iterate the list itself.  But what if the list is potentially huge?  Like an infinite series of numbers?\n",
     "\n",
     "\n",
@@ -299,10 +299,7 @@
    "source": [
     "# fill in this function\n",
     "def fib():\n",
-    "    a, b = 0,1\n",
-    "    while True:\n",
-    "        yield a\n",
-    "        a, b = b, a + b\n",
+    "    pass\n",
     "        \n",
     "# testing code\n",
     "import types\n",