code: async def _port_poll(is_old_bootloader, ports_before_switch=None):
      
      new_port = ''
      while not new_port:
          if is_old_bootloader:
              new_port = await _port_on_mode_switch(ports_before_switch)
          else:
              ports = await _discover_ports()
              if ports:
                  discovered_ports = list(filter(
                      lambda x: x.endswith('bootloader'), ports))
                  if len(discovered_ports) == 1:
                      new_port = '/dev/modules/{}'.format(discovered_ports[0])
          await asyncio.sleep(0.05)
      return new_port
docs: Checks for the bootloader port