title: NLTK makes it easy to compute bigrams of words. What about letters?
body: <p>I've seen tons of documentation all over the web about how the python NLTK makes it easy to compute bigrams of words.</p>
  
  <p>What about letters?</p>
  
  <p>What I want to do is plug in a dictionary and have it tell me the relative frequencies of different letter pairs.</p>
  
  <p>Ultimately I'd like to make some kind of markov process to generate likely-looking (but fake) words.</p>