def autonomous(self):
        """
        Starts an autonomous region for downstream processing.
        By default IBM Streams processing is executed in an autonomous region
        where any checkpointing of operator state is autonomous (independent)
        of other operators.
        
        This method may be used to end a consistent region by starting an
        autonomous region. This may be called even if this stream is in
        an autonomous region.

        Autonomous is not applicable when a topology is submitted
        to a STANDALONE contexts and will be ignored.

        .. versionadded:: 1.6

        Returns:
            Stream: Stream whose subsequent downstream processing is in an autonomous region.
        """
        op = self.topology.graph.addOperator("$Autonomous$")
        op.addInputPort(outputPort=self.oport)
        oport = op.addOutputPort(schema=self.oport.schema)
        return Stream(self.topology, oport)