message: replace supervised session to monitored session
diff: @@ -575,7 +575,7 @@ class _MonitoredSession(object):
  ops.get_default_graph()._unsafe_unfinalize() # pylint: disable=protected-access
  def _is_closed(self):
  - """Return True if the supervised session is closed. For tests only.
  + """Return True if the monitored session is closed. For tests only.
  Returns:
  A boolean.
  