def open
			@serial ||= SerialPort.new @port, @rate
			@serial_input = Enumerator.new { |y| loop do
				y.yield @serial.readbyte
			end }
			@connected = true
		end
def open
			@serial ||= SerialPort.new @port, @rate
			@serial_input = Enumerator.new { |y| loop do
				y.yield @serial.readbyte
			end }
			@connected = true
		end
Either specify the port and serial parameters

   xbee = XBeeRuby::Xbee.new port: '/dev/ttyUSB0', rate: 9600

 or pass in a SerialPort like object

   xbee = XBeeRuby::XBee.new serial: some_serial_mockup_for_testing