title: Specify length of Sequence or List with Python typing module
body: <p>I'm giving the Python <code>typing</code> module a shot.</p>
  
  <p>I know that it's valid to specify the length of a <code>List</code> like the following*:</p>
  
  <pre><code>List[float, float, float]   # List of 3 floats &lt;-- NOTE: this is not valid Python
  </code></pre>
  
  <p>Is there any shorthand for longer lists? What if I want to set it to 10 floats?</p>
  
  <pre><code>List[float * 10]   # This doesn't work.
  </code></pre>
  
  <p>Any idea if this is possible, this would be handy.</p>
  
  <hr>
  
  <p>*NOTE: It turns out that supplying multiple arguments to <code>Sequence[]</code> (and its subclasses) in this manner is currently NOT valid Python. Furthermore, it is currently not possible to specify a <code>Sequence</code> length using the <code>typing</code> module in this way.</p>