title: Error: 'int' object is not subscriptable. ***python-jupyter_notebook
body: <p>I was trying to create a function that accepts an input list (of mixed types), and extracts only numbers from the list.
  <strong>I keep getting this 'int' object is not subscriptable error.</strong></p>
  <pre><code>List = ['M',1,'N',2,'0',3.5]
  a_List = [x[:3] for x in List if type(x)!= str]
  print(a_List)
  </code></pre>