code: function concatTo(obj, key, val) {
      obj[key] = obj[key] || [];
      obj[key] = obj[key].concat(val);
      return obj[key];
  }
docs: Concat To
  : Helper method to ensure array in object property then concat values.
  
  @param obj the object collection containing keys.
  @param key the key to concat values to.
  @param val the array of values to concat.