title: Reverse string: string[::-1] works, but string[0::-1] and others don't
body: <p>I am somewhat of a python/programming newbie, and I have just been playing around with string slicing. So the simple string reverse method of <code>string[::-1]</code> works just fine as we know, but there are other instances in my code below that yields unexpected results:</p>
  
  <pre><code>In [1]: string = "Howdy doody"
  
  In [2]: string[::]
  Out[2]: 'Howdy doody'
  
  In [3]: string[::-1]
  Out[3]: 'ydood ydwoH'
  
  In [4]: string[0:]    
  Out[4]: 'Howdy doody'
  
  In [5]: string[0::-1]
  Out[5]: 'H'     # what up with this?
  
  In [6]: string[:len(string)]
  Out[6]: 'Howdy doody'
  
  In [7]: string[:len(string):-1]
  Out[7]: ''     # what up with this too?
  
  In [8]: string[0:len(string)]
  Out[8]: 'Howdy doody'
  
  In [9]: string[0:len(string):-1]
  Out[9]: ''    # And what up here too.
  </code></pre>
  
  <p>I have commented on the lines above where I expected the strings to be reversed, but I am surprised to see why they don't simply reverse the string. Anyone know what is up with that?</p>