A structure that will be passed to invocation of
LearningProcess.next. Not intended for inspection externally, contains
implementation details of the process.
Metrics derived from the applying the process to a given state and
input. This output is intended for surfacing values to better understand
the progress of a learning process, and is not directly intended to be
used as input to LearningProcess.next. For example, this output may
include classical metrics surrounding the quality of a machine learning
model (eg. the average accuracy of a model across the participating
clients), or operational metrics concerning systems-oriented information
(eg. timing information and the amount of communication occurring between
clients and server).