code: function Log(writer, level, prefix) {
      if (!(this instanceof Log)) return new Log(writer, level, prefix);
      this.writer = writer || process.stdout;
      this.prefix = prefix || '';
      this.level = (typeof level === 'undefined') ? LEVEL.ALL : level;
  }
docs: logger
  
  @examples
  var l = new Log(fd, Log.ALL&~Log.ERROR, '');
  
  @param writer  file's fd
  @param level
  @param prefix
  @returns {Log}
  @constructor