code: def get_user_calibration_factors(band_name, correction_dict):
      """Retrieve radiance correction factors from user-supplied dict."""
      if band_name in correction_dict:
          try:
              slope = correction_dict[band_name]["slope"]
              offset = correction_dict[band_name]["offset"]
          except KeyError:
              raise KeyError(
                  "Incorrect correction factor dictionary. You must "
                  "supply 'slope' and 'offset' keys."
              )
      else:
          # If coefficients not present, warn user and use slope=1, offset=0
          warnings.warn(
              "WARNING: You have selected radiance correction but "
              " have not supplied coefficients for channel "
              + band_name,
              stacklevel=2,
          )
          return 1.0, 0.0
  
      return slope, offset
  
imports: from __future__ import annotations
  import bz2
  import logging
  import os
  import shutil
  import tempfile
  import warnings
  from contextlib import closing, contextmanager
  from io import BytesIO
  from shutil import which
  from subprocess import PIPE, Popen
  import numpy
  import pyproj
  import xarray
  from pyresample.geometry import AreaDefinition
  from satpy import config
  from satpy.readers import FSFile
  from satpy.utils import get_legacy_chunk_size
label_desc: Use image node_id 21 for calling a global function with example usage: get_user_calibration_factors(band_name, correction_dict) and returns: slope,  offset, int,  int