code: def abort(self, err):
          
          if _debug: IOGroup._debug("abort %r", err)
  
          # change the state to reflect that it was killed
          self.ioState = ABORTED
          self.ioError = err
  
          # abort all the members
          for iocb in self.ioMembers:
              iocb.abort(err)
  
          # notify the client
          self.trigger()
docs: Called by a client to abort all of the member transactions.
          When the last pending member is aborted the group callback
          function will be called.