class_docstr: AHI gridded format reader.
  
  This data is flat binary, big endian unsigned short.
  It covers the region 85E -> 205E, 60N -> 60S at variable resolution:
  - 0.005 degrees for Band 3
  - 0.01 degrees for Bands 1, 2 and 4
  - 0.02 degrees for all other bands.
  These are approximately equivalent to 0.5, 1 and 2km.
  
  Files can either be zipped with bz2 compression (like the HSD format
  data), or can be uncompressed flat binary.
docstr: Get the area definition.
  
  This is fixed, but not defined in the file. So we must
  generate it ourselves with some assumptions.
docstr_tok: ["Get","the","area","definition",".","This","is","fixed",",","but","not","defined","in","the","file",".","So","we","must","generate","it","ourselves","with","some","assumptions","."]
code: def get_area_def(self, dsid):
      """Get the area definition.
  
      This is fixed, but not defined in the file. So we must
      generate it ourselves with some assumptions.
      """
      if self.areaname == "fld":
          area_extent = AHI_FULLDISK_EXTENT
      else:
          raise NotImplementedError(
              "Reader only supports full disk data."
          )
  
      proj_param = "EPSG:4326"
  
      area = geometry.AreaDefinition(
          "gridded_himawari",
          "A gridded Himawari area",
          "longlat",
          proj_param,
          self.ncols,
          self.nlines,
          area_extent,
      )
      self.area = area
  
      return area
  
imports: import logging
  import os
  import dask.array
  import numpy
  import xarray
  from appdirs import AppDirs
  from pyresample import geometry
  from satpy.readers.file_handlers import BaseFileHandler
  from satpy.readers.utils import unzip_file
  from satpy.utils import get_legacy_chunk_size
label_desc: Use image node_id 9 for calling the AHIGriddedFileHandler obj's underlying member method code with example usage: obj.get_area_def(dsid) and returns: area