import tensorflow as tf

    assert self.cnf['batch_size_train'] % self.cnf.get('num_gpus', 1) == 0, (
        'Batch size must be divisible by number of GPUs')

    self.inputs = tf.placeholder(
        tf.float32,
        shape=(None, self.model.image_size[0], self.model.image_size[0], 3),
