code: def get_metric(metric_name, export_port):
      res = raw_metrics(export_port)
      for name, samples in res.items():
          if name == metric_name:
              return name, samples
  
      return None
  
imports: import os
  import time
  import sys
  import pytest
  import ray._private.prometheus_exporter
  from typing import List
  from opencensus.stats.view_manager import ViewManager
  from opencensus.stats.stats_recorder import StatsRecorder
  from opencensus.stats import execution_context
  from prometheus_client.core import REGISTRY
  from ray._private.metrics_agent import Gauge, MetricsAgent, Record, RAY_WORKER_TIMEOUT_S
  from ray._private.services import new_port
  from ray.core.generated.metrics_pb2 import Metric, MetricDescriptor, Point, LabelKey, TimeSeries, LabelValue
  from ray._raylet import WorkerID
  from ray._private.test_utils import fetch_prometheus_metrics, fetch_raw_prometheus, wait_for_condition
label_desc: Use image node_id 2 for calling a global function with example usage: get_metric(metric_name, export_port) and returns: None, name,  samples