def __init__(self, memory=None, cores=None, disk=None, preemptable=None):
            self.memory = memory
            self.cores = cores
            self.disk = disk
            self._childServices = []
            self._hasParent = False
            self.preemptable = preemptable
Memory, core and disk requirements are specified identically to as in             :func:`toil.job.Job.__init__`.
dataset/ETHPy150Open BD2KGenomics/toil/src/toil/job.py/Job.Service.__init__