<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _mapreduce_job_counters_metrics(self, running_jobs, auth, ssl_verify, addl_tags):
 """ Get custom metrics specified for each counter """

        for job_metrics in itervalues(running_jobs):
            job_name = job_metrics['job_name']

            # Check if the job_name exist in the custom metrics
            if self.general_counters or (job_name in self.job_specific_counters):
                job_specific_metrics = self.job_specific_counters.get(job_name)

                metrics_json = self._rest_request_to_json(
                    job_metrics['tracking_url'],
                    auth,
                    ssl_verify,
                    'counters',
                    self.MAPREDUCE_SERVICE_CHECK,
                    tags=addl_tags,
                )

                if metrics_json.get('jobCounters'):
                    if metrics_json['jobCounters'].get('counterGroup'):

                        # Cycle through all the counter groups for this job
                        for counter_group in metrics_json['jobCounters']['counterGroup']:
                            group_name = counter_group.get('counterGroupName')

                            if group_name:
                                counter_metrics = set([])

                                # Add any counters in the job specific metrics
                                if job_specific_metrics and group_name in job_specific_metrics:
                                    counter_metrics = counter_metrics.union(job_specific_metrics[group_name])

                                # Add any counters in the general metrics
                                if group_name in self.general_counters:
                                    counter_metrics = counter_metrics.union(self.general_counters[group_name])

                                if counter_metrics:
                                    # Cycle through all the counters in this counter group
                                    if counter_group.get('counter'):
                                        for counter in counter_group['counter']:
                                            counter_name = counter.get('name')

                                            # Check if the counter name is in the custom metrics for this group name
                                            if counter_name and counter_name in counter_metrics:
                                                tags = [
                                                    'app_name:' + job_metrics.get('app_name'),
                                                    'user_name:' + job_metrics.get('user_name'),
                                                    'job_name:' + job_name,
                                                    'counter_name:' + str(counter_name).lower(),
                                                ]

                                                tags.extend(addl_tags)

                                                self._set_metrics_from_json(
                                                    counter, self.MAPREDUCE_JOB_COUNTER_METRICS, tags
                                                )