fit_generator() got an unexpected keyword argument 'samples_per_epoch' code example

Example: fit_generator() got an unexpected keyword argument 'samples_per_epoch'

history_object = model.fit_generator(train_generator, 
                                     steps_per_epoch=samples_per_epoch,
                                      validation_data=validation_generator,
                                      validation_steps=nb_val_samples, 
                                     epochs=nb_epoch, verbose=1,
                                     callbacks=callbacks_list)