'Terminates the specified instance. The desired group size can
also be adjusted, if desired.
:type instance_id: str
:param instance_id: The ID of the instance to be terminated.
:type decrement_capability: bool
:param decrement_capacity: Whether to decrement the size of the
autoscaling group or not.'

def terminate_instance(self, instance_id, decrement_capacity=True):

    params = {'InstanceId': instance_id}
    if decrement_capacity:
        params['ShouldDecrementDesiredCapacity'] = 'true'
    else:
        params['ShouldDecrementDesiredCapacity'] = 'false'
    return self.get_object('TerminateInstanceInAutoScalingGroup', params, Activity)
