class_docstr: A class that stores variables for internal purposes in core during fit
  and predict. For instance, to manage dataflow properties.
docstr: The method allows to combine a mask with features in the form of
  one-dimensional array.
code: def compound_mask(self):
      """The method allows to combine a mask with features in the form of
      one-dimensional array.
      """
  
      input_ids = np.array(
          self.features_mask.get("input_ids"), dtype=str
      )
      flow_lens = np.array(
          self.features_mask.get("flow_lens"), dtype=str
      )
      comp_list = np.core.defchararray.add(input_ids, flow_lens)
      return comp_list
  
file_path: FEDOT/fedot/core/data/supplementary_data.py
imports: from dataclasses import dataclass
  from typing import Dict, Optional
  import numpy
  from fedot.core.repository.operation_types_repository import OperationTypesRepository
  from fedot.core.repository.tasks import TaskTypesEnum
label_desc: Use image node_id 1 for calling the SupplementaryData obj's underlying member method code with example usage: obj.compound_mask() and returns: comp_list