title: Modifying dictionary values while iterating with dict.values() or dict.itervalues()
body: <p>I have a dicionary that is initialized like so:  </p>
  
  <pre><code>tab = {'Mike': 0, 'Chad': 15, 'Taylor': 2}
  </code></pre>
  
  <p>I want to be able to add integers to each value in the dictionary.<br>
  For example, after adding 5, the dictionary should look like this:  </p>
  
  <pre><code>{'Mike': 5, 'Chad': 20, 'Taylor': 7}
  </code></pre>
  
  <p>It seems as if this can be done with a couple of lines of code but I can't figure it out.
  I've tried a for loop:</p>
  
  <pre><code>for k in tab.itervalues():
      k = k + 5
  </code></pre>
  
  <p>I run this code and then print out the dictionary:</p>
  
  <pre><code>tab = {'Mike': 0, 'Chad': 15, 'Taylor': 2}
  </code></pre>
  
  <p>The dictionary has undergone no change. I'm not sure if Python recognizes the values as strings or integers.</p>