code: def restore_sys_modules(scrubbed):
      
      clash = set(sys.modules) & set(scrubbed)
      if len(clash) != 0:
          # If several, choose one arbitrarily to raise an exception about
          first = list(clash)[0]
          raise ImportError('future module {} clashes with Py2 module'
                            .format(first))
      sys.modules.update(scrubbed)
docs: Add any previously scrubbed modules back to the sys.modules cache,
      but only if it's safe to do so.