Footnotes

• Contributors Both authors (TJV and BH) have made substantial contributions to the conception and writing of the working including generating ideas, reviewing literature, drafting the work and revising it critically for important intellectual content and in response to editor and reviewer comments. Both authors also approve of the version being submitted for publication, stand behind its accuracy and integrity and agree to be accountable for all aspects of the work.

• Competing interests None declared.

• Provenance and peer review Not commissioned; internally peer reviewed.