class_docstr: Write data in VISSR archive format.
class_docstr_tok: ["Write","data","in","VISSR","archive","format","."]
code: def _write_image_data(self, fd, contents):
      offset = fmt.IMAGE_DATA[self.ch_type]["offset"]
      self._write(fd, contents["image_data"], offset)
  
imports: import datetime
  import gzip
  import fsspec
  import numpy
  import pytest
  import xarray
  from pyresample.geometry import AreaDefinition
  import satpy.tests.reader_tests.gms.test_gms5_vissr_data
  from satpy.readers import FSFile
  from satpy.tests.reader_tests.utils import get_jit_methods, skip_numba_unstable_if_missing
  from satpy.tests.utils import make_dataid
label_desc: Use image node_id 6 for calling the VissrFileWriter obj's underlying member method code with example usage: obj._write_image_data(fd, contents) without return types