def get_sha(self, ref):
        raise NotImplementedError
Adds a scan node for a certain path specifiation.
dataset/ETHPy150Open getsentry/freight/freight/vcs/base.py/Vcs.get_sha--crossover with--dataset/ETHPy150Open log2timeline/dfvfs/dfvfs/helpers/source_scanner.py/SourceScannerContext.AddScanNode