docs: function Logger( configuration, channels = [] ) {
     this.levels = { ...levels, ...configuration.get( 'logging.levels' ) };
  
     this.queueSize_ = 100;
     this.channels_ = channels;
     this.counter_ = 0;
     this.messageQueue_ = [];
     this.threshold_ = 0;
     this.tags_ = {};
  
     this.levelToName_ = ( levels => {
        const result = {};
        forEach( levels, ( level, levelName ) => {
           this[ levelName.toLowerCase() ] = ( ...args ) => {
              this.log( level, ...args, BLACKBOX );
           };
           result[ level ] = levelName;
        } );
        return result;
     } )( this.levels );
  
     this.setLogThreshold( configuration.ensure( 'logging.threshold' ) );
  }