Perl has autovivication… which is basically automatically creating
undefined fields and assigning them undef when they are accessed.
“Autovivification is both a wonderful blessing and a curse in Perl.”
20190128/DuckDuckGo perl autovivication
20190128/https://en.wikipedia.org/wiki/Autovivification
20190128/https://perlmaven.com/autovivification