docstr: start Unified CloudWatch Agent
docstr_tok: ["start","Unified","CloudWatch","Agent"]
code: def _start_cloudwatch_agent(self, cwa_param_name: str) -> None:
      """start Unified CloudWatch Agent"""
      logger.info(
          "Starting Unified CloudWatch Agent package on node {}.".format(
              self.node_id
          )
      )
      parameters_start_cwa = {
          "action": ["configure"],
          "mode": ["ec2"],
          "optionalConfigurationSource": ["ssm"],
          "optionalConfigurationLocation": [cwa_param_name],
          "optionalRestart": ["yes"],
      }
      self._ssm_command_waiter(
          "AmazonCloudWatch-ManageAgent",
          parameters_start_cwa,
          self.node_id,
      )
      logger.info(
          "Unified CloudWatch Agent started successfully on node {}.".format(
              self.node_id
          )
      )
  
imports: import copy
  import hashlib
  import json
  import logging
  import os
  import time
  from enum import Enum
  from typing import Any, Callable, Dict, List, Union
  import botocore
  from ray.autoscaler._private.aws.utils import client_cache, resource_cache
  from ray.autoscaler.tags import NODE_KIND_HEAD, TAG_RAY_CLUSTER_NAME, TAG_RAY_NODE_KIND
label_desc: Use image node_id 28 for calling the CloudwatchHelper obj's underlying member method code with example usage: obj._start_cloudwatch_agent(cwa_param_name) without return types