code: def checkpoint_dag(checkpoint):
      @ray.remote
      def large_input():
          return np.arange(2**24)
  
      @ray.remote
      def identity(x):
          return x
  
      @ray.remote
      def average(x):
          return np.mean(x)
  
      x = large_input.options(
          **workflow.options(
              task_id="large_input", checkpoint=checkpoint
          )
      ).bind()
      y = identity.options(
          **workflow.options(task_id="identity", checkpoint=checkpoint)
      ).bind(x)
      return workflow.continuation(
          average.options(**workflow.options(task_id="average")).bind(y)
      )
  
file_path: ray/python/ray/workflow/tests/test_checkpoint.py
imports: import ray
  import pytest
  from ray.tests.conftest import *
  import numpy
  from ray import workflow
  from ray._private.client_mode_hook import client_mode_wrap
  from ray.workflow import workflow_storage
  from ray.workflow.tests.utils import assert_task_checkpoints
label_desc: Use image node_id 1 for calling a global function with example usage: checkpoint_dag(checkpoint) and returns: workflow, np, x, np