-;; All the Gnus backends have the same interface, and should return
-;; data in a similar format. Below is and overview of what functions
-;; these packages must supply and what result they should return.
-;;
-;; Variables:
-;;
-;; `nntp-server-buffer' - All data should be returned to Gnus in this
-;; buffer.
-;;
-;; Functions for the imaginary backend `choke':
-;;
-;; `choke-retrieve-headers ARTICLES &optional GROUP SERVER'
-;; Should return all headers for all ARTICLES, or return NOV lines for
-;; the same.
-;;
-;; `choke-request-group GROUP &optional SERVER DISCARD'
-;; Switch to GROUP. If DISCARD is nil, active information on the group
-;; must be returned.
-;;
-;; `choke-close-group GROUP &optional SERVER'
-;; Close group. Most backends won't have to do anything with this
-;; call, but it is an opportunity to clean up, if that is needed. It
-;; is called when Gnus exits a group.
-;;
-;; `choke-request-article ARTICLE &optional GROUP SERVER'
-;; Return ARTICLE, which is either an article number or id.
-;;
-;; `choke-request-list SERVER'
-;; Return a list of all active newsgroups on SERVER.
-;;
-;; `choke-request-list-newsgroups SERVER'
-;; Return a list of descriptions of all newsgroups on SERVER.
-;;
-;; `choke-request-post-buffer METHOD HEADER ARTICLE-BUFFER GROUP INFO'
-;; Should return a buffer that is suitable for "posting". nnspool and
-;; nntp return a `*post-buffer*', and nnmail return a `*mail*'
-;; buffer. This function should fill out the appropriate header
-;; fields.
-;;
-;; `choke-request-post &optional SERVER'
-;; Function that will be called from a buffer to be posted.
-;;
-;; `choke-open-server SERVER &optional ARGUMENT'
-;; Open a connection to SERVER.
-;;
-;; `choke-close-server &optional SERVER'
-;; Close the connection to server.
-;;
-;; `choke-server-opened &optional SERVER'
-;; Whether the server is opened or not.
-;;
-;; `choke-server-status &optional SERVER'
-;; Should return a status string (not in nntp buffer, but as the
-;; result of the function).
-;;
-;; `choke-request-expire-articles ARTICLES &optional NEWSGROUP SERVER'
-;; Should expire (according to some aging scheme) all ARTICLES. Most
-;; backends will not be able to expire articles. Should return a list
-;; of all articles that were not expired.
-;;
-;; All these functions must return nil if they couldn't service the
-;; request. If the optional arguments are not supplied, some "current"
-;; or "default" values should be used. In short, one should emulate an
-;; NNTP server, in a way. All results should be returned in the NNTP
-;; format. (See RFC977).
-