title: coverage.py: exclude files
body: <p>How do I exclude entire files from <a href="http://nedbatchelder.com/code/coverage/" rel="noreferrer">coverage.py</a> reports?</p>
  
  <p>According to the documentation you can exclude code by matching lines. I want to exclude entire files, so that the reports don't include 3rd party libraries. Am I missing something? Can it be done?</p>