code: def get_resources(self, ids, cache=True):
          
          cluster_resources = {}
          for i in ids:
              _, ident = i.rsplit(':', 1)
              parts = ident.split('/', 2)
              if len(parts) != 3:
                  raise PolicyExecutionError("New format ecs arn required")
              cluster_resources.setdefault(parts[1], []).append(parts[2])
  
          results = []
          client = local_session(self.manager.session_factory).client('ecs')
          for cid, resource_ids in cluster_resources.items():
              results.extend(
                  self.process_cluster_resources(client, cid, resource_ids))
          return results
docs: Retrieve ecs resources for serverless policies or related resources
  
          Requires arns in new format.
          https://docs.aws.amazon.com/AmazonECS/latest/userguide/ecs-resource-ids.html