The Publisher apologises for the omission of the funding information. It is as follows:
Acknowledgements
The authors would like to thank the comments made by Tomás Bril-Mascarenhas in the early phases of this project. Sebastian Carrasco acknowledges financial support from Fondecyt de Iniciación (11241196). Aldo Madariaga acknowledges financial support from COES (ANID/FONDAP/1523A0005) and Fondecyt Regular (1240812).
Competing interests
The author(s) declare none