How to use the source-map/array-set.ArraySet.fromArray function in source-map

if (typeof aSourceMap === 'string') {
      sourceMap = JSON.parse(aSourceMap.replace(/^\)\]\}'/, ''));
    }

    var version = util.getArg(sourceMap, 'version');
    var sources = util.getArg(sourceMap, 'sources');
    var names = util.getArg(sourceMap, 'names');
    var sourceRoot = util.getArg(sourceMap, 'sourceRoot', null);
    var mappings = util.getArg(sourceMap, 'mappings');
    var file = util.getArg(sourceMap, 'file');

    if (version !== this._version) {
      throw new Error('Unsupported version: ' + version);
    }

    this._names = ArraySet.fromArray(names);
    this._sources = ArraySet.fromArray(sources);
    this._sourceRoot = sourceRoot;
    this.file = file;

    // `this._generatedMappings` and `this._originalMappings` hold the parsed
    // mapping coordinates from the source map's "mappings" attribute. Each
    // object in the array is of the form
    //
    //     {
    //       generatedLine: The line number in the generated code,
    //       generatedColumn: The column number in the generated code,
    //       source: The path to the original source file that generated this
    //               chunk of code,
    //       originalLine: The line number in the original source that
    //                     corresponds to this chunk of generated code,
    //       originalColumn: The column number in the original source that

sourceMap = JSON.parse(aSourceMap.replace(/^\)\]\}'/, ''));
    }

    var version = util.getArg(sourceMap, 'version');
    var sources = util.getArg(sourceMap, 'sources');
    var names = util.getArg(sourceMap, 'names');
    var sourceRoot = util.getArg(sourceMap, 'sourceRoot', null);
    var mappings = util.getArg(sourceMap, 'mappings');
    var file = util.getArg(sourceMap, 'file');

    if (version !== this._version) {
      throw new Error('Unsupported version: ' + version);
    }

    this._names = ArraySet.fromArray(names);
    this._sources = ArraySet.fromArray(sources);
    this._sourceRoot = sourceRoot;
    this.file = file;

    // `this._generatedMappings` and `this._originalMappings` hold the parsed
    // mapping coordinates from the source map's "mappings" attribute. Each
    // object in the array is of the form
    //
    //     {
    //       generatedLine: The line number in the generated code,
    //       generatedColumn: The column number in the generated code,
    //       source: The path to the original source file that generated this
    //               chunk of code,
    //       originalLine: The line number in the original source that
    //                     corresponds to this chunk of generated code,
    //       originalColumn: The column number in the original source that
    //                       corresponds to this chunk of generated code,