title: Reversed array in numpy?
body: <p><a href="http://www.scipy.org/Tentative_NumPy_Tutorial" rel="noreferrer">Numpy tentative tutorial</a> suggests that <code>a[ : :-1]</code> is a reversed <code>a</code>. Can someone explain me how we got there? </p>
  
  <p>I understand that <code>a[:]</code> means for each element of <code>a</code> (with axis=0). Next <code>:</code> should denote the number of elements to skip (or period) from my understanding.</p>