module Tins::TimeDummy::ClassMethods

def dummy(value = nil)
  if value.nil?
    @dummy
  else
    begin
      old_dummy = @dummy
      @dummy = value
      yield
    ensure
      @dummy = old_dummy
    end
  end
end

def new
  if dummy
    dummy.dup
  else
    really_new
  end
end