title: Moving Keys in dictionary
body: <p>This is my first question, I've read the good posting guide but if I make any mistakes please let me know.</p>
  
  <p>So anyway, I have a dictionary in python that is has keys numbered 1,2,3,4,5, etc and my question is if I delete, say 3, so I have 1,2,4,5 can I change the keys for 4,5 so they become 3,4?</p>
  
  <p>Something like:</p>
  
  <pre><code>mydict = {1:'bob', 2:'sue', 3:'joe', 4:'mary', 5:'billy'}
  
  del mydict[1]
  
  mydict[3] = mydict[4]
  mydict[4] = mydict[5]
  </code></pre>
  
  <p>Thanks in advance.</p>