It would be nice if we could pass in a substring with a wildcard or a regex to get back only certain keys within userdata, readonlydata, titledata, basically anywhere there are key/value pairs.
Example being if we have something like a message system, we might have keys that start with the word message plus some unique numbers after it. I could grab all the message keys by passing in "message*" since it would be difficult to know what the actual key names are and I don't want to grab all the userdata at once to see if they have new messages.