image(imagePath, circularOnly) {
		if (!imagePath) {
			return Promise.reject(new Error('imagePath not provided'));
		}

		return graph.image(
			circularOnly ? this.circularGraph() : this.obj(),
			this.circular(),
			imagePath,
			this.config
		);
	}
Write dependency graph to image.
@api public
@param  {String} imagePath
@param  {Boolean} circularOnly
@return {Promise}