How to use the postman-collection.Collection function in postman-collection

var runner = new Runner(_.merge({}, spec.options)),
        callbacks = {};

    // add a spy for each callback
    _.forEach(_.keys(Runner.Run.triggers), function (eventName) {
        callbacks[eventName] = sinon.spy();
    });

    // the final done callback needs special attention
    callbacks.done = sinon.spy(function () {
        done(null, callbacks, spec);
    });

    // eslint-disable-next-line handle-callback-err
    runner.run(new Collection(spec.collection), _.omit(spec, ['collection', 'options']), function (err, run) {
        run.start(callbacks);
    });
};

ig.forEachItem((el) => {}); // $ExpectType void
ig.forEachItemGroup((el) => {}); // $ExpectType void

ig.oneDeep("string"); // $ExpectType Certificate

pmCollection.ItemGroup.isItemGroup(ig); // $ExpectType boolean

// CollectionDefinition Tests
const colDef: pmCollection.CollectionDefinition = {};
colDef.info; // $ExpectType { id?: string | undefined; name?: string | undefined; version?: string | undefined; } | undefined
colDef.variable; // $ExpectType VariableDefinition | undefined

let collection: pmCollection.Collection;
collection = new pmCollection.Collection();
collection = new pmCollection.Collection({});
collection = new pmCollection.Collection({}, []);

collection.events; // $ExpectType EventList
collection.variables; // $ExpectType VariableList
collection.version; // $ExpectType Version | undefined

collection.syncVariablesFrom({}); // $ExpectType { created: string[]; updated: string[]; deleted: string[]; } | undefined
collection.syncVariablesFrom({}, true); // $ExpectType { created: string[]; updated: string[]; deleted: string[]; } | undefined

collection.syncVariablesTo({}); // ExpectType $ExpectType { [key: string]: VariableDefinition; }

collection.toJSON(); // $ExpectType CollectionDefinition

pmCollection.Collection.isCollection(collection); // $ExpectType boolean

// CookieDefinition Tests

ig.forEachItem((el) => {}); // $ExpectType void
ig.forEachItemGroup((el) => {}); // $ExpectType void

ig.oneDeep("string"); // $ExpectType Certificate

pmCollection.ItemGroup.isItemGroup(ig); // $ExpectType boolean

// CollectionDefinition Tests
const colDef: pmCollection.CollectionDefinition = {};
colDef.info; // $ExpectType { id?: string | undefined; name?: string | undefined; version?: string | undefined; } | undefined
colDef.variable; // $ExpectType VariableDefinition | undefined

let collection: pmCollection.Collection;
collection = new pmCollection.Collection();
collection = new pmCollection.Collection({});
collection = new pmCollection.Collection({}, []);

collection.events; // $ExpectType EventList
collection.variables; // $ExpectType VariableList
collection.version; // $ExpectType Version | undefined

collection.syncVariablesFrom({}); // $ExpectType { created: string[]; updated: string[]; deleted: string[]; } | undefined
collection.syncVariablesFrom({}, true); // $ExpectType { created: string[]; updated: string[]; deleted: string[]; } | undefined

collection.syncVariablesTo({}); // ExpectType $ExpectType { [key: string]: VariableDefinition; }

collection.toJSON(); // $ExpectType CollectionDefinition

pmCollection.Collection.isCollection(collection); // $ExpectType boolean

// CookieDefinition Tests
const cookieDef: pmCollection.CookieDefinition = {

// @TODO - Have to handle global level security scheme

      // Extracing commonly used properties for ease of access throughout the importer
      openapi = validation.openapi;
      openapi.servers = _.isEmpty(openapi.servers) ? [{ url: '/' }] : openapi.servers;
      openapi.securityDefs = _.get(openapi, 'components.securitySchemes', {});
      openapi.baseUrl = _.get(openapi, 'servers.0.url', '{{baseURL}}');

      openapi.baseUrlVariables = _.get(openapi, 'servers.0.variables');

      // Fix {scheme} and {path} vars in the URL to :scheme and :path
      openapi.baseUrl = util.fixPathVariablesInUrl(openapi.baseUrl);

      // Creating a new instance of a Postman collection
      // All generated folders and requests will go inside this
      this.generatedStore.collection = new sdk.Collection({
        info: {
          name: _.get(openapi, 'info.title', COLLECTION_NAME),
          version: _.get(openapi, 'info.version')
        }
      });

      // saving in util for global access
      util.components = openapi.components;
      util.paths = openapi.paths;

      // ---- Collection Variables ----
      // adding the collection variables for all the necessary root level variables
      // and adding them to the collection variables
      util.convertToPmCollectionVariables(
        openapi.baseUrlVariables,
        'baseUrl',

var done = function (err, collection) {
                if (err) {
                    return callback(err);
                }

                // ensure that the collection option is present before starting a run
                if (!_.isObject(collection)) {
                    return callback(new Error(COLLECTION_LOAD_ERROR_MESSAGE));
                }

                // ensure that the collection reference is an SDK instance
                // @todo - should this be handled by config loaders?
                collection = new Collection(Collection.isCollection(collection) ?
                    // if the option contain an instance of collection, we simply clone it for future use
                    // create a collection in case it is not one. user can send v2 JSON as a source and that will be
                    // converted to a collection
                    collection.toJSON() : collection);

                callback(null, collection);
            };

// create and sanitize basic spec
    openapi = this.openapi;
    openapi.servers = _.isEmpty(openapi.servers) ? [{ url: '/' }] : openapi.servers;
    openapi.securityDefs = _.get(openapi, 'components.securitySchemes', {});
    openapi.baseUrl = _.get(openapi, 'servers.0.url', '{{baseURL}}');

    // TODO: Multiple server variables need to be saved as environments
    openapi.baseUrlVariables = _.get(openapi, 'servers.0.variables');

    // Fix {scheme} and {path} vars in the URL to :scheme and :path
    openapi.baseUrl = schemaUtils.fixPathVariablesInUrl(openapi.baseUrl);

    // Creating a new instance of a Postman collection
    // All generated folders and requests will go inside this
    generatedStore.collection = new sdk.Collection({
      info: {
        name: _.get(openapi, 'info.title', COLLECTION_NAME),
        version: _.get(openapi, 'info.version')
      }
    });


    // ---- Collection Variables ----
    // adding the collection variables for all the necessary root level variables
    // and adding them to the collection variables
    schemaUtils.convertToPmCollectionVariables(
      openapi.baseUrlVariables,
      'baseUrl',
      openapi.baseUrl
    ).forEach((element) => {
      generatedStore.collection.variables.add(element);

transformer.convert(content, options, function (error, convertedContent) {

      if (error) {
        callback(error);
        return;
      }

      try {
        var collection = new Collection(convertedContent);
        var result = LuaGenerator.convert(collection)
        callback(null, result);
      } catch(error) {
        callback(error);
      }

    });

initializeCollection: function() {
    	this.collection = new Collection();
    },

convert: function(content, callback) {

    try {
      var collection = new Collection(content);
      var result = LuaGenerator.convert(collection)
      callback(null, result);
    } catch(error) {
      callback(error);
    }

  }

collection;

    options = _.defaults(options, {
        method: 'get',
        url: undefined,
        timeout: undefined,
        ignoreRedirects: false
    });

    userRequest = {
        method: options.method,
        url: options.url,
        header: options.header
    };

    collection = new sdk.Collection({
        item: {
            request: userRequest
        }
    });

    runner.run(collection, {
        timeout: {
            global: options.timeout
        },

        certificates: options.sslClientCert && new sdk.CertificateList({}, [{
            name: 'client-cert',
            matches: [sdk.UrlMatchPattern.MATCH_ALL_URLS],
            key: { src: options.sslClientKey },
            cert: { src: options.sslClientCert },
            passphrase: options.sslClientPassphrase