<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def repl_serial_to_stdout(self, dev):
 """Runs as a thread which has a sole purpose of readding bytes from the serial port and writing them to stdout. Used by do_repl. """

        with self.serial_reader_running:
            try:
                save_timeout = dev.timeout
                # Set a timeout so that the read returns periodically with no data
                # and allows us to check whether the main thread wants us to quit.
                dev.timeout = 1
                while not self.quit_serial_reader:
                    try:
                        char = dev.read(1)
                    except serial.serialutil.SerialException:
                        # This happens if the pyboard reboots, or a USB port
                        # goes away.
                        return
                    except TypeError:
                        # This is a bug in serialposix.py starting with python 3.3
                        # which causes a TypeError during the handling of the
                        # select.error. So we treat this the same as
                        # serial.serialutil.SerialException:
                        return
                    except ConnectionResetError:
                        # This happens over a telnet session, if it resets
                        return
                    if not char:
                        # This means that the read timed out. We'll check the quit
                        # flag and return if needed
                        if self.quit_when_no_output:
                            break
                        continue
                    self.stdout.write(char)
                    self.stdout.flush()
                dev.timeout = save_timeout
            except DeviceError:
                # The device is no longer present.
                return