Fine grained tasks are tracked on github:
- https://github.com/o19s/elasticsearch-learning-to-rank/issues/84
- https://github.com/o19s/elasticsearch-learning-to-rank/issues/83
- https://github.com/o19s/elasticsearch-learning-to-rank/issues/82
- https://github.com/o19s/elasticsearch-learning-to-rank/issues/67
- https://github.com/o19s/elasticsearch-learning-to-rank/issues/80