code: function defaultMetricsKeyBuilder(keyField, tagsFields, fieldName) {
    var keys = [];
    //the key field first
    if (keyField) {
      keys.push(keyField);
    }
    //then tags. statsd doesn't really support tags, so we just add them as part of the key.
    if (tagsFields) {
      var tags = _.map(tagsFields, function(tagValue, tagKey) {
        return tagKey + '_is_' + tagValue; //see https://github.com/vimeo/carbon-tagger
      });
      keys = keys.concat(tags);
    }
    //then the field name
    keys.push(fieldName);
    return keys.join(KEY_DELIMITER);
  }
docs: a default implementation to format the meta data into the name of the metric We will embed tags into the key. Each message will be constructed like this: <key>-<tagKey>_is_<tagValue>...-<fieldName>:<fieldValue>|<type> For example, given this data: {type: 'gauge', key: 'memory', tags: {host: localhost, workerId:1}, fields: {used: 800, total: 1000}} it will be converted to: ['memory-host_is_localhost-workerId_is_1-used:800|g', 'memory-host_is_localhost-workerId_is_1-total:1000|g']