12many – Gen­er­al­is­ing math­e­mat­i­cal in­dex sets

In the dis­crete branches of math­e­mat­ics and the com­puter sci­ences, it will only take some sec­onds be­fore you're faced with a set like {1,...,m}. Some peo­ple write $1\ldotp\ldotp m$, oth­ers $\{j:1\leq j\leq m\}$, and the jour­nal you're sub­mit­ting to might want some­thing else en­tirely. The 12many pack­age pro­vides an in­ter­face that makes chang­ing from one to an­other a one-line change.