The dataset_ops folder contains Theano Ops that provide dataset access to theano
programs.

The protocol.py file sets out the basic convention that is followed by the Ops
in the other files.

For an example of how to set up a dataset whose elements are slices from some
big underlying tensor, see MNIST.py.

For an example of how to set up a dynamically-generated dataset, see
gldataset.py.