code: def format_grammar_string(grammar_dictionary: Dict[str, List[str]]) -> str:
      
      grammar_string = '\n'.join([f"{nonterminal} = {' / '.join(right_hand_side)}"
                                  for nonterminal, right_hand_side in grammar_dictionary.items()])
      return grammar_string.replace("\\", "\\\\")
docs: Formats a dictionary of production rules into the string format expected
      by the Parsimonious Grammar class.