Article History
Received: 2 April 2020
Accepted: 8 June 2020
First Online: 17 June 2020
Compliance with ethical standards
:
: P Ballard: Educational grant from Olympus and Medronic (2019).R Teo: none.A Khunda: Educational grant from Olympus and Medtronic (since 2016).V Kershaw: Educational Grant from Olympus.