Update state of given prediction to active.

        Parameters
        ----------
        experiment_id : string
            Unique experiment identifier
        run_id : string
            Unique model run identifier

        Returns
        -------
        ModelRunHandle
            Handle for updated model run or None is prediction is undefined

def experiments_predictions_update_state_active(self, experiment_id, run_id):
        """Update state of given prediction to active.

        Parameters
        ----------
        experiment_id : string
            Unique experiment identifier
        run_id : string
            Unique model run identifier

        Returns
        -------
        ModelRunHandle
            Handle for updated model run or None is prediction is undefined
        """
        # Get prediction to ensure that it exists
        model_run = self.experiments_predictions_get(experiment_id, run_id)
        if model_run is None:
            return None
        # Update predition state
        return self.predictions.update_state(
            run_id,
            modelrun.ModelRunActive()
        )