function inspect () {
        if (!this.isValid()) {
            return 'moment.invalid(/* ' + this._i + ' */)';
        }
        var func = 'moment';
        var zone = '';
        if (!this.isLocal()) {
            func = this.utcOffset() === 0 ? 'moment.utc' : 'moment.parseZone';
            zone = 'Z';
        }
        var prefix = '[' + func + '("]';
        var year = (0 <= this.year() && this.year() <= 9999) ? 'YYYY' : 'YYYYYY';
        var datetime = '-MM-DD[T]HH:mm:ss.SSS';
        var suffix = zone + '[")]';

        return this.format(prefix + year + datetime + suffix);
    }
Return a human readable representation of a moment that can
also be evaluated to get a new moment which is the same

@link https://nodejs.org/dist/latest/docs/api/util.html#util_custom_inspect_function_on_objects