List blink(1) devices connected, by serial number
        :return: List of blink(1) device serial numbers

def list():
        """
        List blink(1) devices connected, by serial number
        :return: List of blink(1) device serial numbers
        """
        try:
            devs = hid.enumerate(VENDOR_ID,PRODUCT_ID)
            serials = list(map(lambda d:d.get('serial_number'), devs))
            return serials
        except IOError as e:
            return []