title: Why does adding a : to any out of range index on a list slice not return out of range?
body: <p>Why does any slice higher than the length of a list minus 1, not return an error if there is a colon after it?</p>
  
  <p>Example:</p>
  
  <pre><code>IN: a= [1,2,3]
  IN: a[999]
  OUT: IndexError: list index out of range
  
  IN:a[999:]
  OUT: []
  </code></pre>
  
  <p>Thanks!</p>