code: def submission_stream(reddit_session, subreddit, limit=None, verbosity=1):
      
      if six.text_type(subreddit).lower() == "all":
          if limit is None:
              limit = 1000
      if not hasattr(subreddit, 'reddit_session'):
          subreddit = reddit_session.get_subreddit(subreddit)
      return _stream_generator(subreddit.get_new, limit, verbosity)
docs: Indefinitely yield new submissions from the provided subreddit.
  
      Submissions are yielded from oldest to newest.
  
      :param reddit_session: The reddit_session to make requests from. In all the
          examples this is assigned to the variable ``r``.
      :param subreddit: Either a subreddit object, or the name of a
          subreddit. Use `all` to get the submissions stream for all submissions
          made to reddit.
      :param limit: The maximum number of submissions to fetch in a single
          iteration. When None, fetch all available submissions (reddit limits
          this to 1000 (or multiple of 1000 for multi-subreddits). If this number
          is too small, submissions may be missed. Since there isn't a limit to
          the number of submissions that can be retrieved from r/all, the limit
          will be set to 1000 when limit is None.
      :param verbosity: A number that controls the amount of output produced to
          stderr. <= 0: no output; >= 1: output the total number of submissions
          processed and provide the short-term number of submissions processed
          per second; >= 2: output when additional delays are added in order to
          avoid subsequent unexpected http errors. >= 3: output debugging
          information regarding the submission stream. (Default: 1)