code: function writeLog(level, msg) {
    var line;
    if(showSourceInfo) {
      var si = getSourceInfo();
      if (includeDate) {
        line = util.format("[%s] <%s>\t[%s:%s] %s", moment().format(), level, si.file, si.lineNumber, msg);
      } else {
        line = util.format("<%s>\t[%s:%s] %s", level, si.file, si.lineNumber, msg);
      }
    } else {
      if (includeDate) {
        line = util.format("[%s] <%s>\t%s", moment().format(), level, msg);
      } else {
        line = util.format("<%s>\t%s", level, msg);
      }
    }
  
    line += '\n';
    appenders.forEach(function(appender) {
      appender(level, line);
    });
  }
docs: Writes the log to stderr
  
  Partially based on clim (http://github.com/epeli/node-clim)
  Copyright (c) 2009-2011 Esa-Matti Suuronen <esa-matti@suuronen.org>