Text and Data Mining valid from 2019-07-16
Received: 10 December 2018
Accepted: 21 May 2019
First Online: 16 July 2019
Compliance with ethics guidelines
: Xiaolin Fan, Yanzhen Xiong, and Yuan Wang declare there is no conflict of interest. This manuscript is a review article and does not involve a research protocol requiring approval by the relevant institutional review board or ethics committee.