Returns vector features from Mapbox Editor projects
        as GeoJSON or KML.

        Parameters
        ----------
        map_id : str
            The map's unique identifier in the format username.id.

        feature_format : str, optional
            The vector's feature format.

            The default value is json.

        Returns
        -------
        request.Response
            The response object with vector features.

def features(self, map_id, feature_format="json"):
        """Returns vector features from Mapbox Editor projects
        as GeoJSON or KML.

        Parameters
        ----------
        map_id : str
            The map's unique identifier in the format username.id.

        feature_format : str, optional
            The vector's feature format.

            The default value is json.

        Returns
        -------
        request.Response
            The response object with vector features.
        """

        # Validate feature_format.

        feature_format = self._validate_feature_format(feature_format)
   
        # Create dict to assist in building URI resource path.

        path_values = dict(
            map_id=map_id,
            feature_format=feature_format
        )

        # Build URI resource path.

        path_part = "/{map_id}/features.{feature_format}"
        uri = URITemplate(self.base_uri + path_part).expand(**path_values)

        # Send HTTP GET request.

        response = self.session.get(uri)
        self.handle_http_error(response)

        return response