old_contents: #!/usr/bin/env python
  __author__ = 'maxim'
  
  from collection_util import smart_str, str_to_obj
  from data_set import DataSet
  from data_util import read_df, to_changes, to_dataset, split_dataset
  from logging import debug, info, warn, vlog, vlog2, vlog3
  
new_contents: #!/usr/bin/env python
  __author__ = 'maxim'
  
  from collection_util import smart_str, str_to_obj
  from data_set import DataSet
  from data_util import read_df, to_changes, to_dataset, to_dataset_for_prediction, split_dataset
  from logging import debug, info, warn, vlog, vlog2, vlog3
  
subject: add to __init__