class_docstr: Corrected Reflectance (crefl) modifier.
  
  Uses a python rewrite of the C CREFL code written for VIIRS and MODIS.
class_docstr_tok: ["Corrected","Reflectance","(","crefl",")","modifier",".","Uses","a","python","rewrite","of","the","C","CREFL","code","written","for","VIIRS","and","MODIS","."]
code: def _get_registered_dem_cache_key(self):
      if not self.url:
          return
      reg_files = self.register_data_files(
          [{"url": self.url, "known_hash": self.known_hash}]
      )
      return reg_files[0]
  
file_path: satpy/satpy/modifiers/_crefl.py
imports: import logging
  import warnings
  import numpy
  from satpy.aux_download import DataDownloadMixin, retrieve
  from satpy.modifiers import ModifierBase
  from satpy.modifiers.angles import get_angles
label_desc: Use image node_id 2 for calling the ReflectanceCorrector obj's underlying member method code with example usage: obj._get_registered_dem_cache_key() and returns: reg_files