1 Department of Computer Science, City University of Hong Kong, Hong Kong, China.
2 Department of Computer Science, Beijing Normal University - Hong Kong Baptist University United International College, Zhuhai, People's Republic of China.
3 State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, People's Republic of China. zhangxianglilan@gmail.com.
4 Department of Computer Science, City University of Hong Kong, Hong Kong, China. shuaicli@gmail.com.