title: how to import __future__ for keyword-only argument of python 3.0?
body: <p>The following code in python2.6 throws syntax error</p>
  
  <pre><code>&gt;&gt;&gt; def f(a,*args,c):
    File "&lt;stdin&gt;", line 1
      def f(a,*args,c):
                    ^
  SyntaxError: invalid syntax
  </code></pre>
  
  <p>but this syntax is valid in python3.0. I would like to know what should I import in my interpreter to make it work.
  ie. <code>from import __future__ ????</code></p>
  
  <p>for importing <code>print function</code> of 3.0, I would do <code>from __future__ import print_function</code></p>
  
  <p>similarly this defination is invalid in 2.6</p>
  
  <pre><code>def f(a,*b,c=5,**kwargs):
  </code></pre>
  
  <p>while it is legal in 3.0</p>