How to use the esptool.ESP8266ROMFirmwareImage function in esptool

def make_image(args):
    image = ESP8266ROMFirmwareImage()
    if len(args.segfile) == 0:
        raise FatalError('No segments specified')
    if len(args.segfile) != len(args.segaddr):
        raise FatalError('Number of specified files does not match number of specified addresses')
    for (seg, addr) in zip(args.segfile, args.segaddr):
        data = open(seg, 'rb').read()
        image.segments.append(ImageSegment(addr, data))
    image.entrypoint = args.entrypoint
    image.save(args.output)

def __init__(self, load_file=None):
        super(ESP8266ROMFirmwareImage, self).__init__()
        self.flash_mode = 0
        self.flash_size_freq = 0
        self.version = 1

        if load_file is not None:
            segments = self.load_common_header(load_file, ESPLoader.ESP_IMAGE_MAGIC)

            for _ in range(segments):
                self.load_segment(load_file)
            self.checksum = self.read_checksum(load_file)

def LoadFirmwareImage(chip, filename):
    """ Load a firmware image. Can be for ESP8266 or ESP32. ESP8266 images will be examined to determine if they are
        original ROM firmware images (ESP8266ROMFirmwareImage) or "v2" OTA bootloader images.

        Returns a BaseFirmwareImage subclass, either ESP8266ROMFirmwareImage (v1) or ESP8266V2FirmwareImage (v2).
    """
    with open(filename, 'rb') as f:
        if chip.lower() == 'esp32':
            return ESP32FirmwareImage(f)
        else:  # Otherwise, ESP8266 so look at magic to determine the image type
            magic = ord(f.read(1))
            f.seek(0)
            if magic == ESPLoader.ESP_IMAGE_MAGIC:
                return ESP8266ROMFirmwareImage(f)
            elif magic == ESPBOOTLOADER.IMAGE_V2_MAGIC:
                return ESP8266V2FirmwareImage(f)
            else:
                raise FatalError("Invalid image magic number: %d" % magic)

def elf2image(args):
    e = ELFFile(args.input)
    if args.chip == 'auto':  # Default to ESP8266 for backwards compatibility
        print("Creating image for ESP8266...")
        args.chip = 'esp8266'

    if args.chip == 'esp32':
        image = ESP32FirmwareImage()
        image.secure_pad = args.secure_pad
    elif args.version == '1':  # ESP8266
        image = ESP8266ROMFirmwareImage()
    else:
        image = ESP8266V2FirmwareImage()
    image.entrypoint = e.entrypoint
    image.segments = e.sections  # ELFSection is a subclass of ImageSegment
    image.flash_mode = {'qio':0, 'qout':1, 'dio':2, 'dout': 3}[args.flash_mode]
    image.flash_size_freq = image.ROM_LOADER.FLASH_SIZES[args.flash_size]
    image.flash_size_freq += {'40m':0, '26m':1, '20m':2, '80m': 0xf}[args.flash_freq]

    if args.elf_sha256_offset:
        image.elf_sha256 = e.sha256()
        image.elf_sha256_offset = args.elf_sha256_offset

    image.verify()

    if args.output is None:
        args.output = image.default_output_name(args.input)

def make_image(args):
    image = ESP8266ROMFirmwareImage()
    if len(args.segfile) == 0:
        raise FatalError('No segments specified')
    if len(args.segfile) != len(args.segaddr):
        raise FatalError('Number of specified files does not match number of specified addresses')
    for (seg, addr) in zip(args.segfile, args.segaddr):
        data = open(seg, 'rb').read()
        image.segments.append(ImageSegment(addr, data))
    image.entrypoint = args.entrypoint
    image.save(args.output)

self.write_common_header(f, normal_segments)
            checksum = ESPLoader.ESP_CHECKSUM_MAGIC
            for segment in normal_segments:
                checksum = self.save_segment(f, segment, checksum)
            self.append_checksum(f, checksum)

        # calculate a crc32 of entire file and append
        # (algorithm used by recent 8266 SDK bootloaders)
        with open(filename, 'rb') as f:
            crc = esp8266_crc32(f.read())
        with open(filename, 'ab') as f:
            f.write(struct.pack(b'

self.write_common_header(f, normal_segments)
            checksum = ESPLoader.ESP_CHECKSUM_MAGIC
            for segment in normal_segments:
                checksum = self.save_segment(f, segment, checksum)
            self.append_checksum(f, checksum)

        # calculate a crc32 of entire file and append
        # (algorithm used by recent 8266 SDK bootloaders)
        with open(filename, 'rb') as f:
            crc = esp8266_crc32(f.read())
        with open(filename, 'ab') as f:
            f.write(struct.pack(b'

def LoadFirmwareImage(chip, filename):
    """ Load a firmware image. Can be for ESP8266 or ESP32. ESP8266 images will be examined to determine if they are
        original ROM firmware images (ESP8266ROMFirmwareImage) or "v2" OTA bootloader images.

        Returns a BaseFirmwareImage subclass, either ESP8266ROMFirmwareImage (v1) or ESP8266V2FirmwareImage (v2).
    """
    with open(filename, 'rb') as f:
        if chip.lower() == 'esp32':
            return ESP32FirmwareImage(f)
        else:  # Otherwise, ESP8266 so look at magic to determine the image type
            magic = ord(f.read(1))
            f.seek(0)
            if magic == ESPLoader.ESP_IMAGE_MAGIC:
                return ESP8266ROMFirmwareImage(f)
            elif magic == ESPBOOTLOADER.IMAGE_V2_MAGIC:
                return ESP8266V2FirmwareImage(f)
            else:
                raise FatalError("Invalid image magic number: %d" % magic)