code: def _fingerprint_dict_with_files(self, option_val):
      
      return stable_option_fingerprint({
        k: self._expand_possible_file_value(v) for k, v in option_val.items()
      })
docs: Returns a fingerprint of the given dictionary containing file paths.
  
      Any value which is a file path which exists on disk will be fingerprinted by that file's
      contents rather than by its path.
  
      This assumes the files are small enough to be read into memory.
  
      NB: The keys of the dict are assumed to be strings -- if they are not, the dict should be
      converted to encode its keys with `stable_option_fingerprint()`, as is done in the `fingerprint()`
      method.