keras: fit_generator complains validation_freq is unexpected keyword

Hello. Love Keras! I have a relatively straight-forward call in my code to fit_generator but it is returning that one of the parameters (validation_freq) is unexpected. However, all the documentation and even the code to fit_generator shows it is an acceptable parameter.

The call, where parallel_model is an object of type Sequential

  parallel_model.compile(loss='categorical_crossentropy',
    optimizer=rms,
    metrics=['accuracy'])
  train_generator = parallel_model.fit_generator(
    generator=complex_data_generator(x_data, y_data, config),
    epochs=400,
    steps_per_epoch=(len(y_data)/DEFAULT_BATCH_SIZE),
    callbacks=callbacks,
    validation_data=(vx_data, vy_data),
    validation_freq=10)

The error response:

Traceback (most recent call last):
  File "train.py", line 102, in <module>
    validation_freq=10)
  File "/usr/local/lib/python2.7/dist-packages/keras/legacy/interfaces.py", line 91, in wrapper
    return func(*args, **kwargs)
TypeError: fit_generator() got an unexpected keyword argument 'validation_freq'

Keras & Tensorflow Versions

>>> import keras
Using TensorFlow backend.
>>> keras.__version__
'2.2.4'
>>> import tensorflow
>>> tensorflow.__version__
'1.13.1'

Perhaps this is user error on my behalf but I do not think this is expected behavior given the docs. Thanks!