title: Python underscore as a function parameter
body: <p>I have a python specific question. What does a single underscore <code>_</code> as a parameter means?
  I have a function calling <code>hexdump(_)</code>. The _ was never defined, so I guess it has some special value, I could not find a reference telling me what it means on the net. I would be happy if you could tell me.</p>