How to use the diagnostics/logger.LogLevel.WARN function in diagnostics

            e => this.logger.log(LogLevel.WARN, `Error receiving crumb ${e}`),
        );

export function warn(
    this: Observable,
    logger: Logger,
    identifier: string,
    level: ObservableReportLevel = ObservableReportLevel.ERROR,
): Observable {
    return log(this, LogLevel.WARN, logger, identifier, level)
}

function safeDisplay(logger: Logger, obj: any): any {
    try {
        return JSON.stringify(obj)
    } catch (e) {
        logger.log(LogLevel.WARN, `unable to stringify input, exception ${e}`)
        return obj
    }
}

            e => this.logger.log(LogLevel.WARN, `Error receiving crumb ${e}`),
        );

function log(
    o: Observable,
    logLevel: LogLevel,
    logger: Logger,
    identifier: string,
    reportLevel: ObservableReportLevel,
): Observable {
    if (environment.Production && logLevel < LogLevel.WARN) {
        return o
    }
    return o.do(
        v => {
            if (reportLevel & ObservableReportLevel.SUCCESS) {
                logger.log(logLevel, `${identifier} succeeded, result: ${safeDisplay(logger, v)}`)
            }
        },
        e => {
            if (reportLevel & ObservableReportLevel.ERROR) {
                logger.log(logLevel, `${identifier} failed, exception: ${safeDisplay(logger, e)}`)
            }
        },
        () => {
            if (reportLevel & ObservableReportLevel.COMPLETE) {
                logger.log(logLevel, `${identifier} completed`)