Ruby 2.6 added options to Exception#full_message
Learn about options which Expection#full_message accepts
Learn about options which Expection#full_message accepts
Learn about using Maxtrix#antisymmetric?
Learn about freezing middleware with rack-freeze
Learn about the argument which Kernel#system accepts
Learn more about ruby by contributing to RubySpec
Learn about the updated error message output by IO#close