StoppingHighestDose-class: Stop when the highest dose is reached
In 0liver0815/onc-crmpack-test: Object-Oriented Implementation of CRM Designs

Stop when the highest dose is reached

## for example this can be used in the following way:
## we would like to stop if:
## - next proposed dose is highest dose
## - there are already at least 3 patients on that dose
## - we are sure that this dose is safe, e.g. the
## probability to be in the interval (0%, 20%) of DLT
## rate is above 50%.
## This would be implemented as the following combination:

stopHigh <-
  StoppingHighestDose() &
  StoppingPatientsNearDose(nPatients=3, percentage=0) &
  StoppingTargetProb(target=c(0, 0.2),
                     prob=0.5)

## of course this rule would then need to be combined
## with the other standard rules for when to stop
## when the MTD is found based on being near
## e.g. a 30% DLT probability or having reached maximal sample
## size, in the manner of:
## stopRule <- stopHigh | stopLow | stopSamplesize