message: Remove unnecessary import of callbacks
diff: @@ -31,7 +31,6 @@ from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor_shape
  from tensorflow.python.framework import test_util as tf_test_util
  from tensorflow.python.keras import metrics as metrics_module
  -from tensorflow.python.keras import callbacks
  from tensorflow.python.keras import testing_utils
  from tensorflow.python.keras.engine.training_utils import weighted_masked_objective
  from tensorflow.python.keras.utils.generic_utils import slice_arrays
  