code: function setupLogger(name, cfg) {
    assume(name).is.a('string');
    if (cfg) {
      assume(cfg).is.an('object');
      assume(cfg).not.includes('name');
    } else {
      cfg = {};
    }
    cfg.name = name;
  
    // Sometimes, just make it easy to have everything show the file and line
    // number.  This is supposed to be quite slow, so the name is what it is to
    // make it impossible to claim you didn't know it made things slow
    if (process.env.FORCE_LOG_LINE_NUMBERS_AND_BE_SLOW === '1') {
      cfg.src = true;
    }
  
    // We want to be able to override whatever the library or application has
    // specified by changing only an evironment variable.
    let envLevel = parseEnvironment(process.env.LOG_LEVEL, cfg);
    let oldLevel = cfg.level;
    cfg.level = envLevel;
  
    cfg.serializers = {
      err: bunyan.stdSerializers.err,
    };
  
    let logger = bunyan.createLogger(cfg);
  
    // But let's make it clear that we did this by logging
    if (oldLevel) {
      if (oldLevel !== envLevel) {
        logger.warn({
          requested: oldLevel,
          used: envLevel,
        }, 'using log level from environment instead of code');
      }
    }
  
    assume(logger).does.not.include('debugCompat');
    logger.debugCompat = makeCompat(logger);
    return logger;
  }
docs: Create a root logger with the name given by name.  The object returned from
  this function is a root logger.  The design is that each service, component
  or library will use a single root logger object that's initialised a single
  time.
  
  A configuration can be passed in as the second parameter.  This object must
  be a valid bunyan logging configuration.