Footnotes

• Contributors CB and FV conceived of the presented idea. CB, FV and FE wrote the manuscript with support from FA and LF. All authors discussed the results and contributed to the final manuscript.

• 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; internally peer reviewed.