/**
 * Generates PNG and SVG files from a Vega-Lite chart specification
 * @param chartSpec - The Vega-Lite chart specification
 * @param filename - Base filename without extension
 * @param outputDir - Directory to save the files (default: current directory)
 * @returns Promise that resolves when files are generated
 */
export declare function generateChartFiles(chartSpec: any, filename: string, outputDir?: string): Promise<void>;
/**
 * Generates only a PNG file from a Vega-Lite chart specification
 * @param chartSpec - The Vega-Lite chart specification
 * @param filename - Base filename without extension
 * @param outputDir - Directory to save the file (default: current directory)
 * @returns Promise that resolves when file is generated
 */
export declare function generatePNGChart(chartSpec: any, filename: string, outputDir?: string): Promise<void>;
/**
 * Generates only an SVG file from a Vega-Lite chart specification
 * @param chartSpec - The Vega-Lite chart specification
 * @param filename - Base filename without extension
 * @param outputDir - Directory to save the file (default: current directory)
 * @returns Promise that resolves when file is generated
 */
export declare function generateSVGChart(chartSpec: any, filename: string, outputDir?: string): Promise<void>;
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