[rules-users] detecting when an object has not been inserted

Hello, The documentation mentions detecting when an object of certain type with certain values has NOT been inserted within a certain amount of time.for instance if you have one reading above a threshold and want to see if you've received an auxillary reading within specs within the last 10 seconds or so, and if you haven't then take some other action. Is there a sample of doing this( detecting the absence of a certain object type with certain values within the last [10 seconds] or so)? Thanks, Chris