code: def abort(self, reason):
          
          if _debug: ServerSSM._debug("abort %r", reason)
  
          # change the state to aborted
          self.set_state(ABORTED)
  
          # return an abort APDU
          return AbortPDU(True, self.invokeID, reason)
docs: This function is called when the application would like to abort the
          transaction.  There is no notification back to the application.