method private lex: Cf_message.t -> ('y * int) Cf_lex.t
(** Parse the octet buffer by calling [self#lex] in a loop until no
- more output objects are parsed.
+ more output objects are parsed. Returns [None] if no output is
+ recognized, otherwise returns [Some (output, length)] where
+ [output] is a list of events of type ['y] and [length] is the
+ number octets to shift with [self#shift_octets] in the [shift]
method private parse: ('y list * int) option