title: How to get combined code coverage over multiple runs of Python script
body: <p>I've got a python program which is tested by running it several times with different inputs, and comparing the outputs against reference results.</p>
  
  <p>I'd like to get code coverage of all the tests combined, so I can see if there are extra sets of inputs I should be using to get complete coverage.  I've looked at the coverage module but can't work out how I can make it do this.</p>
  
  <p>Any clues?</p>