Quickly returns a small synthetic dataset, useful for unit tests, etc.

Each client produced has exactly 10 examples, one of each digit. The images are derived from a fixed set of hard-coded images, and transformed using tff.simulation.datasets.emnist.get_infinite to produce the desired number of clients.

num_clients The number of synthetic clients to generate.

A tff.simulation.ClientData object that matches the characteristics (other than size) of those provided by tff.simulation.datasets.emnist.load_data.