class_docstr: Use mlflow to implement ExpManager.
code: def list_experiments(self):
      # retrieve all the existing experiments
      exps = self.client.list_experiments(
          view_type=ViewType.ACTIVE_ONLY
      )
      experiments = dict()
      for exp in exps:
          experiment = MLflowExperiment(
              exp.experiment_id, exp.name, self.uri
          )
          experiments[exp.name] = experiment
      return experiments
  
imports: from urllib.parse import urlparse
  import mlflow
  from filelock import FileLock
  from mlflow.exceptions import MlflowException, RESOURCE_ALREADY_EXISTS, ErrorCode
  from mlflow.entities import ViewType
  import os
  from typing import Optional, Text
  from .exp import MLflowExperiment, Experiment
  from ..config import C
  from .recorder import Recorder
  from ..log import get_module_logger
  from ..utils.exceptions import ExpAlreadyExistError
label_desc: Use image node_id 8 for calling the MLflowExpManager obj's underlying member method code with example usage: obj.list_experiments() and returns: experiments