title: What do * and ** before a variable name mean in a function signature?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/1769403/understanding-kwargs-in-python">Understanding kwargs in Python</a>  </p>
  </blockquote>
  
  
  
  <p>I have read a piece of python code, and I don't know what does * and ** mean in this code : </p>
  
  <pre><code>def functionA(self, *a, **kw):
     // code here
  </code></pre>
  
  <p>I just know about one use of *: extract all attribute it has to parameter of method or constructor.</p>
  
  <p>If this true for above function, so what does the rest : ** ?</p>