code: def augment(self, resources):
          
          # First if we're in event based lambda go ahead and skip this,
          # tags can't be trusted in ec2 instances immediately post creation.
          if not resources or self.manager.data.get(
                  'mode', {}).get('type', '') in (
                      'cloudtrail', 'ec2-instance-state'):
              return resources
  
          # AWOL detector, so we don't make extraneous api calls.
          resource_count = len(resources)
          search_count = min(int(resource_count % 0.05) + 1, 5)
          if search_count > resource_count:
              search_count = resource_count
          found = False
          for r in random.sample(resources, search_count):
              if 'Tags' in r:
                  found = True
                  break
  
          if found:
              return resources
  
          # Okay go and do the tag lookup
          client = utils.local_session(self.manager.session_factory).client('ec2')
          tag_set = self.manager.retry(
              client.describe_tags,
              Filters=[{'Name': 'resource-type',
                        'Values': ['instance']}])['Tags']
          resource_tags = {}
          for t in tag_set:
              t.pop('ResourceType')
              rid = t.pop('ResourceId')
              resource_tags.setdefault(rid, []).append(t)
  
          m = self.manager.get_model()
          for r in resources:
              r['Tags'] = resource_tags.get(r[m.id], ())
          return resources
docs: EC2 API and AWOL Tags
  
          While ec2 api generally returns tags when doing describe_x on for
          various resources, it may also silently fail to do so unless a tag
          is used as a filter.
  
          See footnote on for official documentation.
          https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Using_Tags.html#Using_Tags_CLI
  
          Apriori we may be using custodian to ensure tags (including
          name), so there isn't a good default to ensure that we will
          always get tags from describe_x calls.