code: def __set_keras_backend(self, backend):
      if K.backend() != backend:
          current_dim = K.image_dim_ordering()
          os.environ["KERAS_BACKEND"] = backend
          from six.moves import reload_module
  
          reload_module(K)
          K.set_image_dim_ordering(current_dim)
          assert K.backend() == backend
          assert K.image_dim_ordering() == current_dim
      # Make theano backend compatible with Python3
      if backend == "theano":
          from theano import ifelse
  
imports: from __future__ import print_function
  import numpy
  from keras.models import Sequential, Model
  from keras.layers.core import *
  from keras.layers.convolutional import *
  from keras.layers import Dense, Dropout, Input
  from keras.optimizers import RMSprop
  from bigdl.dllib.utils.common import *
  from bigdl.dllib.keras.converter import *
  from bigdl.dllib.keras.converter import WeightLoader, WeightsConverter
  import numpy
  from unittest import TestCase
  import keras
  from bigdl.dllib.nn.keras.keras_utils import *
label_desc: Use image node_id 13 for calling the BigDLTestCase obj's underlying member method code with example usage: obj.__set_keras_backend(backend) without return types