How to use the esptool.ImageSegment function in esptool

def load_segment(self, f, is_irom_segment=False):
        """ Load the next segment from the image file """
        file_offs = f.tell()
        (offset, size) = struct.unpack('

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)

if pad_len < 0:
                    pad_len += IROM_ALIGN
                return pad_len

            # try to fit each flash segment on a 64kB aligned boundary
            # by padding with parts of the non-flash segments...
            while len(flash_segments) > 0:
                segment = flash_segments[0]
                pad_len = get_alignment_data_needed(segment)
                if pad_len > 0:  # need to pad
                    if len(ram_segments) > 0 and pad_len > self.SEG_HEADER_LEN:
                        pad_segment = ram_segments[0].split_image(pad_len)
                        if len(ram_segments[0].data) == 0:
                            ram_segments.pop(0)
                    else:
                        pad_segment = ImageSegment(0, b'\x00' * pad_len, f.tell())
                    checksum = self.save_segment(f, pad_segment, checksum)
                    total_segments += 1
                else:
                    # write the flash segment
                    assert (f.tell() + 8) % IROM_ALIGN == segment.addr % IROM_ALIGN
                    checksum = self.save_segment(f, segment, checksum)
                    flash_segments.pop(0)
                    total_segments += 1

            # flash segments all written, so write any remaining RAM segments
            for segment in ram_segments:
                checksum = self.save_segment(f, segment, checksum)
                total_segments += 1

            if self.secure_pad:
                # pad the image so that after signing it will end on a a 64KB boundary.

class EspCoreDumpTaskStatus(BinStruct):
    """Core dump status structure"""
    # task status flags for note
    TASK_STATUS_CORRECT = 0x00
    TASK_STATUS_TCB_CORRUPTED = 0x01
    TASK_STATUS_STACK_CORRUPTED = 0x02
    fields = ("task_index",
              "task_flags",
              "task_tcb_addr",
              "task_stack_start",
              "task_stack_len",
              "task_name")
    format = "

if pad_len < 0:
                    pad_len += IROM_ALIGN
                return pad_len

            # try to fit each flash segment on a 64kB aligned boundary
            # by padding with parts of the non-flash segments...
            while len(flash_segments) > 0:
                segment = flash_segments[0]
                pad_len = get_alignment_data_needed(segment)
                if pad_len > 0:  # need to pad
                    if len(ram_segments) > 0 and pad_len > self.SEG_HEADER_LEN:
                        pad_segment = ram_segments[0].split_image(pad_len)
                        if len(ram_segments[0].data) == 0:
                            ram_segments.pop(0)
                    else:
                        pad_segment = ImageSegment(0, b'\x00' * pad_len, f.tell())
                    checksum = self.save_segment(f, pad_segment, checksum)
                    total_segments += 1
                else:
                    # write the flash segment
                    assert (f.tell() + 8) % IROM_ALIGN == segment.addr % IROM_ALIGN
                    checksum = self.save_segment(f, segment, checksum)
                    flash_segments.pop(0)
                    total_segments += 1

            # flash segments all written, so write any remaining RAM segments
            for segment in ram_segments:
                checksum = self.save_segment(f, segment, checksum)
                total_segments += 1

            if self.secure_pad:
                # pad the image so that after signing it will end on a a 64KB boundary.

def copy_with_new_addr(self, new_addr):
        """ Return a new ImageSegment with same data, but mapped at
        a new address. """
        return ImageSegment(new_addr, self.data, 0)

def copy_with_new_addr(self, new_addr):
        """ Return a new ImageSegment with same data, but mapped at
        a new address. """
        return ImageSegment(new_addr, self.data, 0)

def load_segment(self, f, is_irom_segment=False):
        """ Load the next segment from the image file """
        file_offs = f.tell()
        (offset, size) = struct.unpack('

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.addr += split_len
        self.file_offs = None
        result.file_offs = None
        return result

    def __repr__(self):
        r = "len 0x%05x load 0x%08x" % (len(self.data), self.addr)
        if self.file_offs is not None:
            r += " file_offs 0x%08x" % (self.file_offs)
        return r

    def pad_to_alignment(self, alignment):
        self.data = pad_to(self.data, alignment, b'\x00')


class ELFSection(ImageSegment):
    """ Wrapper class for a section in an ELF image, has a section
    name as well as the common properties of an ImageSegment. """
    def __init__(self, name, addr, data):
        super(ELFSection, self).__init__(addr, data)
        self.name = name.decode("utf-8")

    def __repr__(self):
        return "%s %s" % (self.name, super(ELFSection, self).__repr__())


class BaseFirmwareImage(object):
    SEG_HEADER_LEN = 8
    SHA256_DIGEST_LEN = 32

    """ Base class with common firmware image functions """
    def __init__(self):