code: function getMetadataFromRules (rulesData) {
    var metadata = [];
  
    rulesData.forEach(function (ruleData) {
      var rule = new Rule(ruleData);
  
      if (_isBucketsMetadata(rule)) {
        metadata.push(new BucketsMetadata(rule));
      } else if (_isCategoriesMetadata(rule)) {
        metadata.push(new CategoriesMetadata(rule));
      }
    });
  
    return metadata;
  }
docs: Generates a list of Metadata objects from the original cartocss_meta rules
  
  @param  {Rules} rulesData
  @return {metadata.Base[]}