Add the following as a new Probulator Function in the rule Probulator Functions:

Name: LEFTMOST
Output Range: True, LOOP, ERROR, False
Forecast Output: Qubit Entanglement
Method: If this method is being run as part of another method return LOOP. Otherwise, select the Probulator Function whose name matches the Forecast Output and use it to determine an outcome, if the determined outcome is the leftmost value in that Function’s output range (or, if the range is not specified as a list, matches the default value for the output range) update the forecast output of this function it to be True, if not update the forecast output of this function to be False. Then update the Forecast Output to be the name of the Probulator Function immediately below the current one in the Probulator Functions list, or the name of the first function in the Probulator Function list if the current one is the bottom most entry. If there is no Probulator Function whose name matches the Forecast Output, return ERROR and set the Forecast Output to be the name of the first function in the Probulator Function list.