code: def _umask(self):
          
          if self.filesystem.is_windows_fs:
              # windows always returns 0 - it has no real notion of umask
              return 0
          if sys.platform == 'win32':
              # if we are testing Unix under Windows we assume a default mask
              return 0o002
          else:
              # under Unix, we return the real umask;
              # as there is no pure getter for umask, so we have to first
              # set a mode to get the previous one and then re-set that
              mask = os.umask(0)
              os.umask(mask)
              return mask
docs: Return the current umask.