code: def umount(mountpoint, persist=False):
      
      cmd_args = ['umount', mountpoint]
      try:
          subprocess.check_output(cmd_args)
      except subprocess.CalledProcessError as e:
          log('Error unmounting {}\n{}'.format(mountpoint, e.output))
          return False
  
      if persist:
          return fstab_remove(mountpoint)
      return True
docs: Unmount a filesystem