code: def _get_mapper(self, estimator, method_name):
      # mappings are handled by ModelFrame._get_mapper
      return None
  
imports: import pandas
  import pandas.compat
  from pandas_ml.compat import Appender
  from pandas_ml.core.base import _BaseEstimator
  from pandas_ml.core.frame import ModelFrame
  from pandas_ml.core.generic import ModelPredictor, _shared_docs
  from pandas_ml.core.series import ModelSeries
label_desc: Use image node_id 2 for calling the ModelFrameGroupBy obj's underlying member method code with example usage: obj._get_mapper(estimator, method_name) and returns: None