<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _GetFileNames(self):
 """Returns a list of file names in the feed."""

    if self._zip:
      return self._zip.namelist()
    else:
      return os.listdir(self._path)