title: Removing duplicates in lists
body: <p>Pretty much I need to write a program to check if a list has any duplicates and if it does it removes them and returns a new list with the items that weren't duplicated/removed. This is what I have but to be honest I do not know what to do.</p>
  <pre><code>def remove_duplicates():
      t = ['a', 'b', 'c', 'd']
      t2 = ['a', 'c', 'd']
      for t in t2:
          t.append(t.remove())
      return t
  </code></pre>