Mysql2の例外のみ補足したい

example.rb

def main(raise_class)
  raise raise_class, 'try rescue!'
rescue Mysql2::Error
  puts "catch #{$!}"
rescue
  puts "Through #{$!}"
end

main(Mysql2::Error)
main(Mysql2::Error::TimeoutError)
main(Mysql2::Error::ConnectionError)
main(StandardError)
main(ArgumentError)