class_docstr: Class implementing the MTG FCI L1c Filehandler.
  
  This class implements the Meteosat Third Generation (MTG) Flexible
  Combined Imager (FCI) Level-1c NetCDF reader.
  It is designed to be used through the :class:`~satpy.Scene`
  class using the :mod:`~satpy.Scene.load` method with the reader
  ``"fci_l1c_nc"``.
docstr: Calibrate data.
docstr_tok: ["Calibrate","data","."]
code: def calibrate(self, data, key):
      """Calibrate data."""
      if key["calibration"] in [
          "brightness_temperature",
          "reflectance",
          "radiance",
      ]:
          data = self.calibrate_counts_to_physical_quantity(data, key)
      elif key["calibration"] != "counts":
          logger.error(
              "Received unknown calibration key.  Expected "
              "'brightness_temperature', 'reflectance', 'radiance' or 'counts', got "
              + key["calibration"]
              + "."
          )
  
      return data
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import logging
  from datetime import timedelta
  from functools import cached_property
  import dask.array
  import numpy
  import xarray
  from netCDF4 import default_fillvals
  from pyresample import geometry
  from satpy.readers._geos_area import get_geos_area_naming
  from satpy.readers.eum_base import get_service_mode
  from .netcdf_utils import NetCDF4FsspecFileHandler
label_desc: Use image node_id 21 for calling the FCIL1cNCFileHandler obj's underlying member method code with example usage: obj.calibrate(data, key) and returns: data