code: def _load_instance(self, instance_id):
          
          # if instance is known, return it
          if instance_id in self._instances:
              return self._instances[instance_id]
  
          # else, check (cached) list from provider
          if instance_id not in self._cached_instances:
              self._cached_instances = self._build_cached_instances()
  
          if instance_id in self._cached_instances:
              inst = self._cached_instances[instance_id]
              self._instances[instance_id] = inst
              return inst
  
          # If we reached this point, the instance was not found neither
          # in the caches nor on the website.
          raise InstanceNotFoundError(
              "Instance `{instance_id}` not found"
              .format(instance_id=instance_id))
docs: Return instance with the given id.
  
          For performance reasons, the instance ID is first searched for in the
          collection of VM instances started by ElastiCluster
          (`self._instances`), then in the list of all instances known to the
          cloud provider at the time of the last update
          (`self._cached_instances`), and finally the cloud provider is directly
          queried.
  
          :param str instance_id: instance identifier
          :return: py:class:`boto.ec2.instance.Reservation` - instance
          :raises: `InstanceError` is returned if the instance can't
                   be found in the local cache or in the cloud.