add slide on reading plain text files

Author: afeld

extras/test_lectures.py

@@ -41,7 +41,7 @@ def num_slides_without_tag(cells, tag):
     return num_slides(tagged_cells)
 
 
-# see counts with `pytest -s -k num_slides`
+# see counts with `pytest -s -vv -k num_slides`
 @pytest.mark.parametrize("file", lecture_notebooks)
 def test_num_slides(file):
     """Ensure there are a reasonable number of slides for each school"""

lecture_1.ipynb

@@ -4,9 +4,11 @@
    "cell_type": "code",
    "execution_count": 1,
    "metadata": {
+    "editable": true,
     "slideshow": {
      "slide_type": "skip"
-    }
+    },
+    "tags": []
    },
    "outputs": [],
    "source": [
@@ -119,6 +121,30 @@
     "https://docs.python.org/3/tutorial/modules.html"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {
+    "editable": true,
+    "slideshow": {
+     "slide_type": "slide"
+    },
+    "tags": [
+     "columbia-only"
+    ]
+   },
+   "source": [
+    "## Working with files in Python\n",
+    "\n",
+    "We'll open the file, then read it row by row.\n",
+    "\n",
+    "```python\n",
+    "# set up the file object\n",
+    "with open(\"moby_dick.txt\") as file:\n",
+    "    for line in file:\n",
+    "        print(line)\n",
+    "```"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {