code: def test_get_head_node_id():
      """Test get_head_node_id() returning the correct head node id.
  
      When there are woker node, dead head node, and other alive head nodes,
      get_head_node_id() should return the node id of the first alive head node.
      When there are no alive head nodes, get_head_node_id() should raise assertion error.
      """
      nodes = [
          {
              "NodeID": "worker_node1",
              "Alive": True,
              "Resources": {"CPU": 1},
          },
          {
              "NodeID": "dead_head_node1",
              "Alive": False,
              "Resources": {"CPU": 1, HEAD_NODE_RESOURCE_NAME: 1.0},
          },
          {
              "NodeID": "alive_head_node1",
              "Alive": True,
              "Resources": {"CPU": 1, HEAD_NODE_RESOURCE_NAME: 1.0},
          },
          {
              "NodeID": "alive_head_node2",
              "Alive": True,
              "Resources": {"CPU": 1, HEAD_NODE_RESOURCE_NAME: 1.0},
          },
      ]
      with patch("ray.nodes", return_value=nodes):
          assert get_head_node_id() == "alive_head_node1"
  
      with patch("ray.nodes", return_value=[]):
          with pytest.raises(AssertionError):
              get_head_node_id()
  
imports: import asyncio
  import json
  import os
  import time
  from unittest.mock import patch
  import numpy
  import pytest
  from fastapi.encoders import jsonable_encoder
  import ray
  from ray import serve
  from ray._private.resource_spec import HEAD_NODE_RESOURCE_NAME
  from ray._private.test_utils import wait_for_condition
  from ray.serve._private.test_utils import MockTimer
  from ray.serve._private.utils import MetricsPusher, calculate_remaining_timeout, get_all_live_placement_group_names, get_current_actor_id, get_head_node_id, is_running_in_asyncio_loop, merge_dict, msgpack_deserialize, msgpack_serialize, override_runtime_envs_except_env_vars, serve_encoders, snake_to_camel_case
  from ray.serve.tests.common.remote_uris import TEST_DAG_PINNED_URI, TEST_DEPLOY_GROUP_PINNED_URI
label_desc: Use image node_id 8 for calling a global function with example usage: test_get_head_node_id() without return types