code: def get_metrics_csv(self, experiment):
      return StringIO()
  
imports: import logging
  from io import StringIO
  from neptune.common.utils import NoopObject
  from neptune.legacy.backend import BackendApiClient, LeaderboardApiClient
label_desc: Use image node_id 7 for calling the OfflineLeaderboardApiClient obj's underlying member method code with example usage: obj.get_metrics_csv(experiment) and returns: StringIO