def BackendsRollback(self):
    if len(self.args) != 1:
      self.parser.error('Expected a single <backend> argument.')

    self._Rollback(self.args[0])
Equivalent of unix `chmod +w path`
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/tools/appcfg.py/AppCfgApp.BackendsRollback--crossover with--dataset/ETHPy150Open pantsbuild/pex/pex/common.py/chmod_plus_w