title: Python slice without copy?
body: <p>Is there a way to create a "slice view" of a sequence in Python 3 that behaves like a regular slice but does not create a copy of the sliced part of the sequence?  When the original sequence is updated, the "slice view" should reflect the update.</p>
  
  <pre><code>&gt;&gt;&gt; l = list(range(100))
  &gt;&gt;&gt; s = Slice(l, 1, 50, 3)  # Should behave like l[1:50:3]
  &gt;&gt;&gt; s[1]
  4
  &gt;&gt;&gt; l[4] = 'foo'
  &gt;&gt;&gt; s[1]  # Should reflect the updated value
  'foo'
  </code></pre>
  
  <p>I can write my own <code>Slice</code> class that does this but I wanted to find out if there was a built-in way.</p>