class_docstr: Handle a single SCMI NetCDF4 file.
class_docstr_tok: ["Handle","a","single","SCMI","NetCDF4","file","."]
docstr: Figure out which grid mapping should be used.
docstr_tok: ["Figure","out","which","grid","mapping","should","be","used","."]
code: def _get_cf_grid_mapping_var(self):
      """Figure out which grid mapping should be used."""
      gmaps = [
          "fixedgrid_projection",
          "goes_imager_projection",
          "lambert_projection",
          "polar_projection",
          "mercator_projection",
      ]
      if "grid_mapping" in self.filename_info:
          gmaps = [self.filename_info.get("grid_mapping")] + gmaps
      for grid_mapping in gmaps:
          if grid_mapping in self.nc:
              return self.nc[grid_mapping]
      raise KeyError("Can't find grid mapping variable in SCMI file")
  
imports: import logging
  import os
  from datetime import datetime
  import numpy
  import xarray
  from pyresample import geometry
  from satpy.readers.file_handlers import BaseFileHandler
  from satpy.utils import get_legacy_chunk_size
label_desc: Use image node_id 7 for calling the SCMIFileHandler obj's underlying member method code with example usage: obj._get_cf_grid_mapping_var() and returns: self