Most rubyists know you can define a method on a single object like so:

logger = Logger.new(STDOUT)

def logger.flush
  puts 'flushed log'
end

logger.flush #=> 'flushed log'

Which means you can replace the logger in def logger.flush with almost anything. For example, lets turn that previous snippet into a one liner:

def (logger = Logger.new(STDOUT)).flush;  puts('flushed log'); end

logger.flush #=> 'flushed log'