terminal() function not found

[aloaloSU]

I am trying to perform a shared frailty model as follows:

emfrail(Surv(Start, Stop, Event) ~ cluster(id) + terminal(death) + x1 + x2, data = dat).

The Start variable indicates the beginning of the time interval; Stop indicates the end of the time interval when an event occurs. Id is the unique identifier variable, and death is a status indicator where 0=alive and 1=dead. I am interested to see how the recurrent event process is affected by informative censoring.

When I try to implement the shared frailty model, unfortunately, R (version 4.3.1) throws the error "Error in terminal(death): could not find function "terminal"". Do you know what could possibly be the problem?

Thank you very much for your help in advance!