Added cat commands to slides

diff --git a/slides/caesar-encipher.html b/slides/caesar-encipher.html
index 4afd78dad4f3367c5107a99d0f40ff8f1e0aa037..279c2bdf8aa96de2b978f9e012381fcb57705a71 100644 (file)
--- a/slides/caesar-encipher.html
+++ b/slides/caesar-encipher.html
@@ -90,7 +90,7 @@ Before doing anything, create a new branch in Git
 
 Experiment in IPython (ephemeral, for us)
 
-Once you've got something working, copy the code into a `.py` file (permanent and reusable)
+Once you've got something working, export the code into a `.py` file (permanent and reusable)
 
 ```python
 from imp import reload
@@ -224,6 +224,15 @@ ciphertext = [caesar_encipher_letter(p, key) for p in plaintext]
 ''.join()
 ```
 
+You'll be doing this a lot, so define a couple of utility functions:
+
+```python
+cat = ''.join
+wcat = ' '.join
+```
+
+`cat` after the Unix command (_concatenate_ files), `wcat` for _word concatenate_.
+
     </textarea>
     <script src="http://gnab.github.io/remark/downloads/remark-0.6.0.min.js" type="text/javascript">
     </script>