code: def add_key_value(self, key, value):
          
          key = self._metadata_map.get(key, key)
          if key in ['dateAdded', 'lastModified']:
              self._data[key] = self._utils.format_datetime(value, date_format='%Y-%m-%dT%H:%M:%SZ')
          elif key == 'confidence':
              self._data[key] = int(value)
          elif key == 'rating':
              self._data[key] = float(value)
          elif key == 'unique_id':
              self._unique_id = quote_plus(value)
          else:
              self._data[key] = value
docs: Converts the value and adds it as a data field.
  
          Args:
              key:
              value: