'Adds instances to this load balancer. All instances must be in the same
region as the load balancer. Adding endpoints that are already
registered with the load balancer has no effect.
:param list instances: List of instance IDs (strings) that you\'d like
to add to this load balancer.'

def register_instances(self, instances):

    if isinstance(instances, six.string_types):
        instances = [instances]
    new_instances = self.connection.register_instances(self.name, instances)
    self.instances = new_instances
