code: def exit_code(self, code):
          
          if code is not None and code in [0, 1, 3]:
              self._exit_code = code
          else:
              self.log.warning(u'Invalid exit code')
docs: Set the App exit code.
  
          For TC Exchange Apps there are 3 supported exit codes.
          * 0 indicates a normal exit
          * 1 indicates a failure during execution
          * 3 indicates a partial failure
  
          Args:
              code (integer): The exit code value for the app.