code: def fit(self, ctx, train_data, **kwargs):
      for i, sub_ctx in ctx.on_iterations.ctxs_range(5):
          sub_ctx.metrics.log_auc("auc", i / 5)
  
file_path: FATE/python/fate/components/components/cross_validation_test.py
imports: import logging
  import typing
  from fate.components.core import ARBITER, GUEST, HOST, Role, cpn, params
label_desc: Use image node_id 2 for calling the FakeTrainer obj's underlying member method code with example usage: obj.fit(ctx, train_data) without return types