code: def loss_aggregation(self, ctx, ranks=None):
      return float(
          self.loss_aggregator.secure_aggregate(ctx, ranks=ranks)[0]
      )
  
imports: import logging
  from typing import Optional
  import numpy
  import torch
  from fate.arch import Context
  from fate.arch.protocol.secure_aggregation._secure_aggregation import SecureAggregatorClient
  from fate.arch.protocol.secure_aggregation._secure_aggregation import SecureAggregatorServer
label_desc: Use image node_id 6 for calling the BaseAggregatorServer obj's underlying member method code with example usage: obj.loss_aggregation(ctx, ranks) and returns: float