new_contents: from zope.configuration import xmlconfig
  from zope.component import getUtility
  
  from calc import eval
  
  
  def main():
      # pip install zope.configuration
      xmlconfig.file('configure.zcml')
  
      assert eval('2 + 2') == 4
      assert eval('2 - 2') == 0
  
  
  if __name__ == '__main__':
      main()
  
subject: Create main.py