code: def _parse_sklearn_regressor_chain(topology, model, inputs):
      """
      :param topology: Topology object
      :param model: A *scikit-learn* *RegressorChain* object
      :param inputs: A list of Variable objects
      :return: Output produced by RegressorChain
      """
      outputs = []
      for estimator in model.estimators_:
          outputs.append(
              _parse_sklearn_api(topology, estimator, inputs)[0]
          )
          conc_op = topology.declare_logical_operator("SklearnConcat")
          conc_op.inputs.extend(inputs)
          conc_op.inputs.append(outputs[-1])
          conc_names = topology.declare_logical_variable(
              "concat_inputs"
          )
          conc_op.outputs.append(conc_names)
          inputs = conc_op.outputs
  
      conc_op = topology.declare_logical_operator("SklearnConcat")
      if model.order is not None:
          reorderd_outputs = [None for _ in outputs]
          for i, pos in enumerate(model.order):
              reorderd_outputs[pos] = outputs[i]
          outputs = reorderd_outputs
  
      conc_op.inputs = outputs
      conc_names = topology.declare_logical_variable("concat_outputs")
      conc_op.outputs.append(conc_names)
      return conc_op.outputs
  
imports: from collections import OrderedDict
  from copy import deepcopy
  import pprint
  from uuid import uuid4
  import numpy
  from onnxconverter_common.optimizer import LinkedNode, _topological_sort
  from sklearn import pipeline
  from sklearn.compose import ColumnTransformer
  from sklearn.ensemble import BaggingClassifier, BaggingRegressor
  from sklearn.model_selection import GridSearchCV, RandomizedSearchCV
  from sklearn.multioutput import MultiOutputRegressor, RegressorChain
  from sklearn.preprocessing import OneHotEncoder
  from .containers import CommonSklearnModelContainer, CommonONNXModelContainer, CommonSparkMLModelContainer
  from ._topology import Topology
  from ._utils import sklearn_installed, sparkml_installed
  from .operator_converters import constants
  from .supported import get_sklearn_api_operator_name, get_onnxml_api_operator_name, get_sparkml_api_operator_name
label_desc: Use image node_id 12 for calling a global function with example usage: _parse_sklearn_regressor_chain(topology, model, inputs) and returns: conc_op