docs: def _load_cwr_defaults(self):
          """
          Loads the CWR default values file, creating a matrix from it, and then
          returns this data.
  
          The file will only be loaded once.
  
          :return: the CWR default values matrix
          """
          if self._cwr_defaults is None:
              self._cwr_defaults = self._reader.read_yaml_file(
                  self._file_defaults)
  
          return self._cwr_defaults