export declare class Logger {
    static readonly LEVELS: string[];
    static readonly LEVEL_DEFAULT = "info";
    static readonly get: Logger;
    static isValidLevel(level: string): boolean;
    static validateLevel(level: string): void;
    private static mLog;
    private mPrefix;
    private mColor;
    private mIsOn;
    private mLevel;
    constructor();
    isTraceEnabled(): boolean;
    isDebugEnabled(): boolean;
    isInfoEnabled(): boolean;
    isWarnEnabled(): boolean;
    isErrorEnabled(): boolean;
    isFatalEnabled(): boolean;
    trace(message: string, ...args: any[]): string;
    debug(message: string, ...args: any[]): string;
    info(message: string, ...args: any[]): string;
    warn(message: string, ...args: any[]): string;
    error(message: string, ...args: any[]): string;
    fatal(message: string, ...args: any[]): string;
    private writeStderr;
    private writeStdout;
    private format;
    private buildPrefix;
    readonly formatEnabled: boolean;
    color: boolean;
    on: boolean;
    readonly level: string;
    prefix: boolean;
}