Explicitly set the health status of an instance.

        :type instance_id: str
        :param instance_id: The identifier of the EC2 instance.

        :type health_status: str
        :param health_status: The health status of the instance.
            "Healthy" means that the instance is healthy and should remain
            in service. "Unhealthy" means that the instance is unhealthy.
            Auto Scaling should terminate and replace it.

        :type should_respect_grace_period: bool
        :param should_respect_grace_period: If True, this call should
            respect the grace period associated with the group.

def set_instance_health(self, instance_id, health_status,
                            should_respect_grace_period=True):
        """
        Explicitly set the health status of an instance.

        :type instance_id: str
        :param instance_id: The identifier of the EC2 instance.

        :type health_status: str
        :param health_status: The health status of the instance.
            "Healthy" means that the instance is healthy and should remain
            in service. "Unhealthy" means that the instance is unhealthy.
            Auto Scaling should terminate and replace it.

        :type should_respect_grace_period: bool
        :param should_respect_grace_period: If True, this call should
            respect the grace period associated with the group.
        """
        params = {'InstanceId': instance_id,
                  'HealthStatus': health_status}
        if should_respect_grace_period:
            params['ShouldRespectGracePeriod'] = 'true'
        else:
            params['ShouldRespectGracePeriod'] = 'false'
        return self.get_status('SetInstanceHealth', params)