Well, in a way this is funny. As far as I can see, that example is taken from the page describing the differences between Perl and Raku (https://docs.raku.org/

Well, in a way this is funny. As far as I can see, that example is taken from the page describing the differences between Perl and Raku (https://docs.raku.org/language/5to6-nutshell#CPAN https://docs.raku.org/language/5to6-nutshell#CPAN), and how you can use Perl inside Raku using the Inline::Perl5 module, and how you can load a Perl module that exports a "looks_like_number" subroutine, and use it from Raku. The example for "looks_like_number" has probably be chosen, because many experienced Perl programmers are familiar with that. In Raku, you can use kebab-case, and if there would be such a routine in Raku, it would probably be called "looks-like-number", and return a Bool, as in either True or False. "say" is also builtin in Perl, at least for the past 12 years or so. And if you are on a Mac, running "say this is your computer talking to you', it will talk to you. In any case, the thing you appear to refer to, is in no way a tutorial, but rather documentation intended for a specific group of people: Perl programmers.