How to use the tifffile.TiffTag.Error function in tifffile

try:
            dtype = TIFF_DATA_TYPES[dtype]
        except KeyError:
            raise TiffTag.Error("unknown tag data type %i" % dtype)

        fmt = '%s%i%s' % (byteorder, count*int(dtype[0]), dtype[1])
        size = struct.calcsize(fmt)
        if size > parent.offset_size or code in CUSTOM_TAGS:
            pos = fh.tell()
            tof = {4: 'I', 8: 'Q'}[parent.offset_size]
            self.value_offset = offset = struct.unpack(byteorder+tof, value)[0]
            if offset < 0 or offset > parent._fsize:
                raise TiffTag.Error("corrupt file - invalid tag value offset")
            elif offset < 4:
                raise TiffTag.Error("corrupt value offset for tag %i" % code)
            fh.seek(offset)
            if code in CUSTOM_TAGS:
                readfunc = CUSTOM_TAGS[code][1]
                value = readfunc(fh, byteorder, dtype, count)
                fh.seek(0, 2)  # bug in numpy/Python 3.x ?
                if isinstance(value, dict):  # numpy.core.records.record
                    value = Record(value)
            elif code in TIFF_TAGS or dtype[-1] == 's':
                value = struct.unpack(fmt, fh.read(size))
            else:
                value = read_numpy(fh, byteorder, dtype, count)
                fh.seek(0, 2)  # bug in numpy/Python 3.x ?
            fh.seek(pos)
        else:
            value = struct.unpack(fmt, value[:size])

else:
            name = str(code)

        try:
            dtype = TIFF_DATA_TYPES[dtype]
        except KeyError:
            raise TiffTag.Error("unknown tag data type %i" % dtype)

        fmt = '%s%i%s' % (byteorder, count*int(dtype[0]), dtype[1])
        size = struct.calcsize(fmt)
        if size > parent.offset_size or code in CUSTOM_TAGS:
            pos = fh.tell()
            tof = {4: 'I', 8: 'Q'}[parent.offset_size]
            self.value_offset = offset = struct.unpack(byteorder+tof, value)[0]
            if offset < 0 or offset > parent._fsize:
                raise TiffTag.Error("corrupt file - invalid tag value offset")
            elif offset < 4:
                raise TiffTag.Error("corrupt value offset for tag %i" % code)
            fh.seek(offset)
            if code in CUSTOM_TAGS:
                readfunc = CUSTOM_TAGS[code][1]
                value = readfunc(fh, byteorder, dtype, count)
                fh.seek(0, 2)  # bug in numpy/Python 3.x ?
                if isinstance(value, dict):  # numpy.core.records.record
                    value = Record(value)
            elif code in TIFF_TAGS or dtype[-1] == 's':
                value = struct.unpack(fmt, fh.read(size))
            else:
                value = read_numpy(fh, byteorder, dtype, count)
                fh.seek(0, 2)  # bug in numpy/Python 3.x ?
            fh.seek(pos)
        else:

fmt, size = {4: ('HHI4s', 12), 8: ('HHQ8s', 20)}[parent.offset_size]
        data = fh.read(size)
        code, dtype = struct.unpack(byteorder + fmt[:2], data[:4])
        count, value = struct.unpack(byteorder + fmt[2:], data[4:])

        if code in TIFF_TAGS:
            name = TIFF_TAGS[code][0]
        elif code in CUSTOM_TAGS:
            name = CUSTOM_TAGS[code][0]
        else:
            name = str(code)

        try:
            dtype = TIFF_DATA_TYPES[dtype]
        except KeyError:
            raise TiffTag.Error("unknown tag data type %i" % dtype)

        fmt = '%s%i%s' % (byteorder, count*int(dtype[0]), dtype[1])
        size = struct.calcsize(fmt)
        if size > parent.offset_size or code in CUSTOM_TAGS:
            pos = fh.tell()
            tof = {4: 'I', 8: 'Q'}[parent.offset_size]
            self.value_offset = offset = struct.unpack(byteorder+tof, value)[0]
            if offset < 0 or offset > parent._fsize:
                raise TiffTag.Error("corrupt file - invalid tag value offset")
            elif offset < 4:
                raise TiffTag.Error("corrupt value offset for tag %i" % code)
            fh.seek(offset)
            if code in CUSTOM_TAGS:
                readfunc = CUSTOM_TAGS[code][1]
                value = readfunc(fh, byteorder, dtype, count)
                fh.seek(0, 2)  # bug in numpy/Python 3.x ?