code: def __init__(self, data, sep, group_feature_num=None):
      super(_SimpleDataReader, self).__init__(sep, group_feature_num)
      self._data = pd.DataFrame(data)
  
file_path: catboost/catboost/python-package/catboost/eval/_readers.py
imports: import pandas
  from .utils import series_to_line
label_desc: Use image node_id 1 to create a new _SimpleDataReader object from inherited base classes: _BaseReader with example: obj = _SimpleDataReader(data, sep, group_feature_num)