constructor(initialValues, options) {
        this.config = {}
        this.continueOnError = false
        this.groups = []
        this.maxParallel = 0
        this.npmPath = null
        this.packageConfig = createPackageConfig()
        this.printLabel = false
        this.printName = false
        this.race = false
        this.rest = []
        this.silent = process.env.npm_config_loglevel === "silent"
        this.singleMode = Boolean(options && options.singleMode)

        addGroup(this.groups, initialValues)
    }
@param {object} initialValues - A key-value map for the default of new value.
@param {object} options - A key-value map for the options.