def add_key_value(self, key, value):
        """
        Converts the value and adds it as a data field.

        Args:
            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
Converts the value and adds it as a data field.

        Args:
            key:
            value: