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.
      """
  
      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 distributed.client import Future
  from functools import wraps
  from dask_cudf.core import Series
  from cuml.internals.safe_imports import gpu_only_import_from
  from cuml.internals.base import Base
  from cuml.internals import BaseMetaClass
  from cuml.dask.common import parts_to_ranks
  from cuml.dask.common.input_utils import DistributedDataHandler
  from raft_dask.common.comms import Comms
  from cuml.dask.common.utils import wait_and_raise_from_futures
  from cuml.internals.array import CumlArray
  from cuml.dask.common.utils import get_client
  from collections.abc import Iterable
  from toolz import first
  from cuml.internals.safe_imports import cpu_only_import
  import dask
  import cudf.comm.serialize
  from cuml.internals.safe_imports import gpu_only_import
label_desc: Use image node_id 4 for calling the BaseEstimator obj's underlying member method code with example usage: obj.get_combined_model() and returns: internal_model