docs: def dumps(self, indent=1):
          """ Returns nested string representation of the dictionary (like json.dumps).
  
          :param indent: indentation level.
          """
  
          str_keys_dict = OrderedDict({str(k): v for k, v in self.items()})
          for k, v in str_keys_dict.items():
              if isinstance(v, dict):
                  str_keys_dict[k] = OrderedDict({str(k1): v1 for k1, v1 in v.items()})
                  for k1, v1 in str_keys_dict[k].items():
                      if isinstance(v1, dict):
                          str_keys_dict[k][k1] = OrderedDict({str(k2): v2 for k2, v2 in v1.items()})
          return json.dumps(str_keys_dict, indent=indent)