class_docstr: The class defines the interface of nodes modifying tha data flow in the :class:`Pipeline`
  
  Args:
      operation_type: operation defined in the operation repository
      nodes_from: parent nodes where data comes from
      node_data: ``dict`` with :class:`InputData` for fit and predict stage
      kwargs: optional arguments (i.e. logger)
docstr: Sets ``node_data`` (if exists) and ``fitted_operation`` to ``None``
          
docstr_tok: ["Sets","``","node_data","``","(","if","exists",")","and","``","fitted_operation","``","to","``","None","``"]
code: def unfit(self):
      """Sets ``node_data`` (if exists) and ``fitted_operation`` to ``None``"""
  
      self.fitted_operation = None
      if hasattr(self, "node_data"):
          self.node_data = None
  
imports: from __future__ import annotations
  from dataclasses import dataclass
  from typing import Any, List, Optional, Tuple, Union
  import numpy
  from golem.core.dag.linked_graph_node import LinkedGraphNode
  from golem.core.log import default_log
  from golem.core.optimisers.timer import Timer
  from golem.serializers.serializer import register_serializable
  from fedot.core.data.data import InputData, OutputData
  from fedot.core.data.merge.data_merger import DataMerger
  from fedot.core.operations.factory import OperationFactory
  from fedot.core.operations.operation import Operation
  from fedot.core.operations.operation_parameters import OperationParameters
  from fedot.core.repository.operation_types_repository import OperationTypesRepository
  from fedot.core.utils import DEFAULT_PARAMS_STUB, NESTED_PARAMS_LABEL
label_desc: Use image node_id 11 for calling the PipelineNode obj's underlying member method code with example usage: obj.unfit() without return types