I new in python and machine learning. I tried to implement the following code for federated learning with the MNIST dataset but it doesn’t work !! it tried to train a model in a distributed way in local workers. the jpeg version of the MNIST data set is using here. It consists of 42000 digit images with each class kept in a separate folder. I will load the data into memory using this code snippet and keep 10% of the data for testing the trained global model later on.My error is :