title: Check if Python Package is installed
body: <p>What's a good way to check if a package is installed while within a Python script? I know it's easy from the interpreter, but I need to do it within a script. </p>
  
  <p>I guess I could check if there's a directory on the system that's created during the installation, but I feel like there's a better way. I'm trying to make sure the Skype4Py package is installed, and if not I'll install it.</p>
  
  <p>My ideas for accomplishing the check</p>
  
  <ul>
  <li>check for a directory in the typical install path</li>
  <li>try to import the package and if an exception is throw, then install package</li>
  </ul>