/styles/v1/{username}/{style_id}/tiles/{tileSize}/{z}/{x}/{y}{@2x}

def tile(self, username, style_id, z, x, y, tile_size=512, retina=False):
        "/styles/v1/{username}/{style_id}/tiles/{tileSize}/{z}/{x}/{y}{@2x}"
        if tile_size not in (256, 512):
            raise errors.ImageSizeError('tile_size must be 256 or 512 pixels')

        pth = '/{username}/{style_id}/tiles/{tile_size}/{z}/{x}/{y}'

        values = dict(username=username, style_id=style_id,
                      tile_size=tile_size, z=z, x=x, y=y)

        uri = URITemplate(self.baseuri + pth).expand(**values)
        if retina:
            uri += '@2x'
        res = self.session.get(uri)
        self.handle_http_error(res)
        return res