title: How can I find out whether a GSettings schema exists or not before attempting to use it?
body: <p>If a GSettings schema exists and has been compiled, there is usually no problem reading from it.  However, if it doesn't exist, an error is usually thrown which cannot be handled.  Try this in a Python file or console:</p>
  
  <pre><code>from gi.repository import Gio
  try:
      settings = Gio.Settings("com.example.doesnotexist")
  except:
      print "Couldn't load those settings!"
  </code></pre>
  
  <p>I'm being as broad as possible with the <code>except</code>, but this is the error that is thrown.</p>
  
  <blockquote>
    <p>(process:10248): GLib-GIO-ERROR **: Settings schema 'com.example.doesnotexist' is not installed</p>
  </blockquote>
  
  <p>What I basically want to do is find out if the <code>com.example.doesnotexist</code> schema exists or not; if not, then tell the user to run my setup script before using my application.  Any other suggestions on doing this would be welcome.</p>