title: Python - get slice index
body: <p>Is it possible to get index values (start,end) of a slice? For example</p>
  
  <pre><code>In [1]: s = "Test string"
  In [2]: s[-6:] # get slice indexes (5,11)
  Out[2]: 'string'
  
  
  In [3]: s = "Another test string"
  In [4]: s[8:] # get slice indexes (8,19)
  Out[4]: 'test string'
  </code></pre>
  
  <p>In other words, I don't need the substring itself but only the indexes as a tuple (start,end).</p>