add description and functions comments
add description and functions comments


Former-commit-id: a62abcf0918000f6bae9aba9e5f5b93e96e99988 [formerly 842031bef6e87763e4af288462f3399b62a7982f]
Former-commit-id: a4f15cc52a83b8f09294d3332e6586a43ce26ced
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine