code: def as_data(self):
          
          use_file_if_no_data = not self._data and self._file
          if use_file_if_no_data:
              with open(self._file) as f:
                  if self._base64_file_content:
                      self._data = bytes.decode(
                          base64.standard_b64encode(str.encode(f.read())))
                  else:
                      self._data = f.read()
          return self._data
docs: If obj[%data_key_name] exists, Return obj[%data_key_name] otherwise
          base64 encoded string of obj[%file_key_name] file content.