code: def fit(self, df_features):
      pass
  
file_path: qlib/qlib/contrib/data/highfreq_processor.py
imports: import os
  import numpy
  import pandas
  from qlib.data.dataset.processor import Processor
  from qlib.data.dataset.utils import fetch_df_by_index
  from typing import Dict
label_desc: Use image node_id 2 for calling the HighFreqTrans obj's underlying member method code with example usage: obj.fit(df_features) without return types