code: function(collectionName, collection, fn, separator, keyOverride, parentKey) {
          separator = separator || ', ';
          var $sql = '';
          _.each(collection, function(value, key) {
              $sql += fn(collectionName, value, keyOverride || key, parentKey);
  
              // (always append separator)
              $sql += separator;
          });
  
          // (then remove final one)
          return _.str.rtrim($sql, separator);
      }
docs: Put together the CSV aggregation separator => optional, defaults to ', ' keyOverride => optional, overrides the keys in the dictionary (used for generating value lists in IN queries) parentKey => key of the parent to this object