While brew has an accessible simple versioning mechanism, it's restricted to versions used by a large number of people. So for popular versions, it's easy:
brew search node # gives node@6, node@8, node@10 brew search postgresql #gives firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, postgresql@10 brew search python # gives python@2
And I can install one for instance with
brew install python@2.
But for less popular versions which got removed, let's say
email@example.com, then it's not obvious how to install them:
brew install firstname.lastname@example.org
Error: No available formula with the name "email@example.com"
==> Searching for a previously deleted formula (in the last month)...
Error: No previously deleted formula found.
==> Searching for similarly named formulae...
Error: No similarly named formulae found.
==> Searching taps...
==> Searching taps on GitHub...
Error: No formulae found in taps.