Instructions
Ruby Perl: topics containing "Ruby" or "Perl"+Ruby +Perl: topics containing "Ruby" and "Perl"
"Ruby vs. Perl": topics containing the phrase "Ruby vs. Perl"
Ru*: words beginning with "Ru"
i Ruby -Rails: topics containing "Ruby", but not "Rails"
Rubyinrails~: words similar to "Rubyinrails", e.g. "Rubyonrails"
subject:(+Ruby +Perl): topics containing both "Ruby" and "Perl" in the subject