title: Write a Python method to generate typos based on a string
body: <p>I could just add in something that creates typos based on Levenshtein distance of two, or something like that, or reverse-engineer <a href="http://norvig.com/spell-correct.html" rel="nofollow">Norvig's article on spellchecking</a>.  </p>
  
  <p>However, what are the most common ways to typos?  </p>
  
  <p>Has somebody written a method?</p>