module IRB::Notifier

def def_notifier(prefix = "", output_method = StdioOutputMethod.new)

formatting.
expressions will be sent directly to STDOUT without any additional
no +output_method+ is given, StdioOutputMethod will be used, and all
during output, using the given +output_method+ as the output source. If
The optional +prefix+ will be appended to all objects being inspected

with the given +prefix+ and +output_method+.
Define a new Notifier output source, returning a new CompositeNotifier 
def def_notifier(prefix = "", output_method = StdioOutputMethod.new)
  CompositeNotifier.new(prefix, output_method)
end