code: def _DISPATCH(self, body, ticket=None):
          
          if ticket:
              sticket = '%s' % (shortuuid(ticket), )
          else:
              ticket = sticket = str(next(self.ticket_counter))
          try:
              method, args = itemgetter('method', 'args')(body)
              self.log.info('#%s --> %s',
                            sticket, self._reprcall(method, args))
              act = self.lookup_action(method)
              r = {'ok': act(args or {})}
              self.log.info('#%s <-- %s', sticket, reprkwargs(r))
          except self.Next:
              raise
          except Exception as exc:
              einfo = sys.exc_info()
              r = {'nok': [safe_repr(exc), self._get_traceback(einfo)]}
              self.log.error('#%s <-- nok=%r', sticket, exc)
          return dict(self._default_fields, **r)
docs: Dispatch message to the appropriate method
          in :attr:`state`, handle possible exceptions,
          and return a response suitable to be used in a reply.
  
          To protect from calling special methods it does not dispatch
          method names starting with underscore (``_``).
  
          This returns the return value or exception error
          with defaults fields in a suitable format to be used
          as a reply.
  
          The exceptions :exc:`SystemExit` and :exc:`KeyboardInterrupt`
          will not be handled, and will propagate.
  
          In the case of a successful call the return value will
          be::
  
              {'ok': return_value, **default_fields}
  
          If the method raised an exception the return value
          will be::
  
              {'nok': [repr exc, str traceback], **default_fields}
  
          :raises KeyError: if the method specified is unknown
          or is a special method (name starting with underscore).