Installer ss3
    project: 'Scratch-fbs';
    install: 'Pharo-Compatibility-fbs.2.mcz'

It still only contains a single method, but instead of Symbol >>
#isBinary, it's String >> #includesSubstring:.

I wouldn't mind seeing this applied in trunk - and will, if people
like it (and moving #includesSubString: to 45Deprecated) - but for now
this is where you find the stuff you need for your favourite
#includesSubstring:-using Pharo package.

frank