Received: 10 January 2020
Accepted: 19 May 2020
First Online: 29 July 2020
Ethics approval and consent to participate
: This study involved a systematic search of the literature only; it did not require ethics approval or consent to participate.
: All authors consent to this manuscript’s publication in the order in which the authors are listed in the cover sheet.
: The authors declare that they have no competing interests.