title: Reliably detect Windows in Python
body: <p>I'm working on a couple of Linux tools and need to prevent installation on Windows, since it depends on FHS and is thus rendered useless on that platform. The <code>platform.platform</code> function comes close but only returns a string.</p>
  
  <p>Unfortunately I don't know what to search for in that string for it to yield a reliable result. Does anyone know what to search for or does anyone know of another function that I'm missing here?</p>