How to split to 3 datasets?

validation_split parameter is able to allow ImageDataGenerator to split the data sets reading from the folder into 2 different disjoint sets. Is there any way to create 3 sets - of training, validation, and evaluation datasets using it?

I am thinking about splitting the dataset into 2 datasets, then splitting the 2nd dataset into another 2 datasets

datagen = ImageDataGenerator(validation_split=0.5, rescale=1./255)

train_generator = datagen.flow_from_directory(
    TRAIN_DIR, 
    subset='training'
)

val_generator = datagen.flow_from_directory(
    TRAIN_DIR,
    subset='validation'
)

Here I am thinking about splitting the validation dataset into 2 sets using val_generator. One for validation and the other for evaluation? How should I do it?

from How to split to 3 datasets?