docs: function mergeData (to, from) {
  	  var key, toVal, fromVal;
  	  for (key in from) {
  	    toVal = to[key];
  	    fromVal = from[key];
  	    if (!hasOwn(to, key)) {
  	      set(to, key, fromVal);
  	    } else if (isObject(toVal) && isObject(fromVal)) {
  	      mergeData(toVal, fromVal);
  	    }
  	  }
  	  return to
  	}