async function combineSourceMapChainFast (inputMapChain, original_code, filepath) {
    let mapGenerator, mapChain = prepareSourceMapChain(inputMapChain, original_code, filepath);

    if (mapChain.length > 1) {
        mapGenerator = SourceMapFast.SourceMapGenerator.fromSourceMap(await new SourceMapFast.SourceMapConsumer(mapChain[0].map));

        for (let i = 1; i < mapChain.length; i++) {
            mapGenerator.applySourceMap(await new SourceMapFast.SourceMapConsumer(mapChain[i].map))
        }
    }
    
    return generateSourceMap(mapChain, mapGenerator, original_code, filepath);
}
@param {NollupTransformMapEntry[]} inputMapChain 
@param {string} original_code 
@param {string} filepath 
@return {Promise<RollupSourceMap>}