docs: def __update_stack_with_isotopes_infos(self, stack: dict):
          """retrieve the isotopes, isotopes file names, mass and atomic_ratio from each element in stack"""
          for _key in stack:
              _elements = stack[_key]['elements']
              for _element in _elements:
                  _dict = _utilities.get_isotope_dicts(element=_element, database=self.database)
                  stack[_key][_element] = _dict
  
          stack = self.__fill_missing_keys(stack=stack)
          return stack