Merge commit '3f8e158a9dd27cc4c02be4e55fd51670563217d5' * commit '3f8e158a9dd27cc4c02be4e55fd51670563217d5': add class description and revise descriptions for
Merge commit '3f8e158a9dd27cc4c02be4e55fd51670563217d5' * commit '3f8e158a9dd27cc4c02be4e55fd51670563217d5': add class description and revise descriptions for