Footnotes

• Contributors MG and JB participated in the conception of the article. MG performed the literature review, wrote the initial draft, and prepared the figures. MG and JB reviewed and edited the final draft.

• Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial, or not-for-profit sectors.

• Competing interests None declared.

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