class Net::SSH::Transport::HMAC::Abstract

def etm(*v)
  @etm = false if !defined?(@etm)
  if v.empty?
    @etm = superclass.etm if @etm.nil? && superclass.respond_to?(:etm)
    return @etm
  elsif v.length == 1
    @etm = v.first
  else
    raise ArgumentError, "wrong number of arguments (#{v.length} for 1)"
  end
end