class_docstr: Base class for file handler calibration tests.
class_docstr_tok: ["Base","class","for","file","handler","calibration","tests","."]
code: def _get_expected(
      self, channel, calibration, calib_mode, use_ext_coefs
  ):
      if use_ext_coefs:
          return self.expected[channel][calibration]["EXTERNAL"]
      return self.expected[channel][calibration][calib_mode]
  
imports: import unittest
  from datetime import datetime
  import numpy
  import pytest
  import xarray
  from satpy.readers.seviri_base import SEVIRICalibrationAlgorithm, SEVIRICalibrationHandler
label_desc: Use image node_id 2 for calling the TestFileHandlerCalibrationBase obj's underlying member method code with example usage: obj._get_expected(channel, calibration, calib_mode, use_ext_coefs) and returns: self, self