code: def timeline(filename=None):
      """Return a list of profiling events that can viewed as a timeline.
  
      Ray profiling must be enabled by setting the RAY_PROFILING=1 environment
      variable prior to starting Ray, and RAY_task_events_report_interval_ms set
      to be positive (default 1000)
  
      To view this information as a timeline, simply dump it as a json file by
      passing in "filename" or using using json.dump, and then load go to
      chrome://tracing in the Chrome web browser and load the dumped file.
  
      Args:
          filename: If a filename is provided, the timeline is dumped to that
              file.
  
      Returns:
          If filename is not provided, this returns a list of profiling events.
              Each profile event is a dictionary.
      """
      return state.chrome_tracing_dump(filename=filename)
  
imports: import json
  import logging
  from collections import defaultdict
  from typing import Set
  from google.protobuf.json_format import MessageToDict
  import ray
  from ray._private.client_mode_hook import client_mode_hook
  from ray._private.resource_spec import NODE_ID_PREFIX, HEAD_NODE_RESOURCE_NAME
  from ray._private.utils import binary_to_hex, decode, hex_to_binary, validate_actor_state_name
  from ray._raylet import GlobalStateAccessor
  from ray.core.generated import common_pb2
  from ray.core.generated import gcs_pb2
  from ray.util.annotations import DeveloperAPI
label_desc: Use image node_id 8 for calling a global function with example usage: timeline(filename) and returns: state