title: Removing duplicate characters from a string
body: <p>How can I remove duplicate characters from a string using Python? For example, let's say I have a string:</p>
  
  <pre><code>foo = 'mppmt'
  </code></pre>
  
  <p>How can I make the string:</p>
  
  <pre><code>foo = 'mpt'
  </code></pre>
  
  <p>NOTE: Order is not important</p>