The publisher regrets that the following code was displayed within the article: “[baseline=(char.base)] [shape = circle, draw, inner sep = 1.5 pt] (char) 1”, [baseline=(char.base)] [shape = circle, draw, inner sep = 1.5 pt] (char) 2, and [baseline=(char.base)] [shape = circle, draw, inner sep = 1.5 pt] (char) 3”. Instead the format should have been as follows: ‘1, 2 and 3’. The publisher would like to apologise for any inconvenience caused.