Creates a baseline task for next-word prediction on Stack Overflow.

The goal of the task is to take sequence_length words from a post and predict the next word. Here, all posts are drawn from the Stack Overflow forum, and a client corresponds to a user.

train_client_spec A tff.simulation.baselines.ClientSpec specifying how to preprocess train client data.
eval_client_spec An optional tff.simulation.baselines.ClientSpec specifying how to preprocess evaluation client data. If set to None, the evaluation datasets will use a batch size of 64 with no extra preprocessing.
sequence_length A positive integer dictating the length of each word sequence in a client's dataset. By default, this is set to tff.simulation.baselines.stackoverflow.DEFAULT_SEQUENCE_LENGTH.
vocab_size Integer dictating the number of most frequent words in the entire corpus to use for the task's vocabulary. By default, this is set to tff.simulation.baselines.stackoverflow.DEFAULT_WORD_VOCAB_SIZE.
num_out_of_vocab_buckets The number of out-of-vocabulary buckets to use.
cache_dir An optional directory to cache the downloadeded datasets. If None, they will be cached to ~/.tff/.
use_synthetic_data A boolean indicating whether to use synthetic Stack Overflow data. This option should only be used for testing purposes, in order to avoid downloading the entire Stack Overflow dataset. A synthetic vocabulary will also be used (not necessarily of the size vocab_size).

A tff.simulation.baselines.BaselineTask.