code: def cover(session):
      
      session.interpreter = 'python3.6'
      session.install('coverage', 'pytest-cov')
      session.run('coverage', 'report', '--show-missing', '--fail-under=100')
      session.run('coverage', 'erase')
docs: Run the final coverage report.
      This outputs the coverage report aggregating coverage from the unit
      test runs (not system test runs), and then erases coverage data.