docs: def _compile_new_relic_stats(self, stats_this_second, stats_next_second):
          """
          from instance 'stats_this_second' and instance 'stats_next_second', compute some per
          second stats metrics and other aggregated metrics
  
          :param dict stats_this_second:
          :param dict stats_next_second:
          :return: compiled instance stats that has metrics
  
          {'opcounters_per_node_per_second': {...},
           'server_statistics_per_second': {...},
           'aggregate_server_statistics': {...},
           'replication_lag': 0.0,
           'aggregate_database_statistics': {}
           }
          """
          server_statistics_per_second = {}
          opcounters_per_node_per_second = []
          for subdoc in ["opcounters", "network"]:
              first_doc = stats_this_second['aggregate_server_statistics'][subdoc]
              second_doc = stats_next_second['aggregate_server_statistics'][subdoc]
              keys = set(first_doc.keys()) | set(second_doc.keys())
              server_statistics_per_second[subdoc] = {key: int(second_doc[key]) - int(first_doc[key]) for key in keys if isinstance(first_doc[key], int)}
          for node1, node2 in zip(stats_this_second['opcounters_per_node'], stats_next_second['opcounters_per_node']):
              node_opcounters_per_second = {}
              for repl, members in node2.items():
                  node_opcounters_per_second[repl] = {}
                  for member, ops in members.items():
                      node_opcounters_per_second[repl][member] = {}
                      for op, count in ops.items():
                          node_opcounters_per_second[repl][member][op] = count - node1[repl][member][op]
              opcounters_per_node_per_second.append(node_opcounters_per_second)
  
          return {'opcounters_per_node_per_second': opcounters_per_node_per_second,
                  'server_statistics_per_second': server_statistics_per_second,
                  'aggregate_server_statistics': stats_next_second.get('aggregate_server_statistics'),
                  'replication_lag': stats_next_second.get('replication_lag'),
                  'aggregate_database_statistics': self.get_aggregate_database_stats()}