class_docstr: BaseRandomForestModel defines functions used in both Random Forest
  Classifier and Regressor for Multi Node and Multi GPU models. The common
  functions are defined here and called from the main Random Forest Multi
  Node Multi GPU APIs. The functions defined here are not meant to be used
  as a part of the public API.
docstr: Return single-GPU model for serialization.
  
  Returns
  -------
  
  model : Trained single-GPU model or None if the model has not
          yet been trained.
docstr_tok: ["Return","single-GPU","model","for","serialization",".","Returns","--","--","--","-","model",":","Trained","single-GPU","model","or","None","if","the","model","has","not","yet","been","trained","."]
code: def get_combined_model(self):
      """
      Return single-GPU model for serialization.
  
      Returns
      -------
  
      model : Trained single-GPU model or None if the model has not
              yet been trained.
      """
  
      # set internal model if it hasn't been accessed before
      if self._get_internal_model() is None:
          self._set_internal_model(self._concat_treelite_models())
  
      internal_model = self._check_internal_model(
          self._get_internal_model()
      )
  
      if isinstance(self.internal_model, Iterable):
          # This function needs to return a single instance of cuml.Base,
          # even if the class is just a composite.
          raise ValueError(
              "Expected a single instance of cuml.Base "
              "but got %s instead." % type(self.internal_model)
          )
  
      elif isinstance(self.internal_model, Future):
          internal_model = self.internal_model.result()
  
      return internal_model
  
imports: from cuml.fil.fil import TreeliteModel
  from cuml.dask.common.utils import get_client, wait_and_raise_from_futures
  from cuml.dask.common.input_utils import DistributedDataHandler, concatenate
  from dask.distributed import Future
  from collections.abc import Iterable
  from cuml import using_output_type
  import warnings
  from cuml.internals.safe_imports import gpu_only_import
  import dask
  import json
  import math
  from cuml.internals.safe_imports import cpu_only_import
label_desc: Use image node_id 12 for calling the BaseRandomForestModel obj's underlying member method code with example usage: obj.get_combined_model() and returns: internal_model